University researchers are developing concepts and methods that pertain to increasing conversion efficiency in silicon solar cells and photodetectors. (more...)

This invention is a new process to create microlens arrays and microwells in plastic.Microlenses are primarily fabricated from glass and optical grade polymers. One such plastic is polystyrene (PS), which has a high index of refraction, high optical transmission, and spectral band pass. Glass microlens array production is comparatively older but polymers have been favored for their affordability and ease of manufacture as well as the ability to control their thermal and mechanical properties. Previous methods for polymer arrays include: photoresist reflow, microjet printing, and direct laser writing. High temperature reflow of photoresist to create such rounded high aspect ratio structures is difficult and often results in rather shallow lenses. Then, to transfer the patterns into hard plastics via hot embossing, costly and slow electroplating is required. Instead, we created our molds using a laser jet printer and a technique which solves the shortcomings of modern manufacturing techniques. We address the issue of microfabricating high aspect ratio structures with high curvature (deep and round). Reflow of photoresist, the common way to make such structures typically results in shallow radii of curvature structures. Moreover, to transfer such structures to hard plastics typically require hot embossing, which requires a metallized (e.g. nickel electroplated) mold. This is very slow and expensive. Our technique allows our masters to be created with a laserjet printer. Then we can do soft lithography to transfer this to PDMS. Finally, we use the PDMS mold for the hot embossing back into a thermoplastic sheet. One problem solved by plastic microwells is the culturing of embryoid bodies (EB). EBs require size, morphology, uniformity and reproducibility control. Previous methods often required a trade-off between quantity and uniformity. PDMS microwells were a great improvement and did much to address these concerns. PDMS have the drawbacks of non-selective absorption, swelling, and poor mechanicalproperties. Polymer microlens arrays have been seen to have much potential but popular techniques for fabrication have various problems. For example,photoresist reflow suffers from chemical and thermal instability, has high requirements for consistency and reproducibility, and need photosensitive material. Some such disadvantages have been overcome but very often require expensive equipment and a time consuming process. This is new method of creating features on the microscale. The inverse of features previously formed in polydimethylsiloxane (PDMS) is transferred to a thermoplastic such as prestressed polystyrene. This is performed by placing the thermoplastic on the PDMS mold, forcing the substrates towards one another through uniform pressure, and baking them past the glass transition temperature of the thermoplastic. Inherent in this process are the multitude of techniques to pattern in PDMS and the ability of thermoplastics to become malleable when properly heated. The purpose of this is to create microstructures that may be used in various applications such as embryoid body culture or optical communication and interconnection. To demonstrate ability of the microlens arrays, we conducted a simple laser experiment was performed. As the laser was shown through the 460 um microlens array a z-stack of images were acquired. Using this information the numerical aperture for several lens were calculated to approximately 0.14. With this demonstration the functionality of this new microlens array design has been proven. This new, inexpensive and relatively simple method to fabricate microlens arrays in a hard plastic with excellent optical properties can provide a platform for optical applications. (more...)

University researchers have developed methods, systems and devices relating to the integrated recording, representation and recreation of sight, sound, touch, smell and taste that extend current audio and video capabilities. Potential applications are broad, including consumer electronics, entertainment, communication, e‐health/medical care. (more...)

A system that exploits the synchronization properties of coupled, nonlinear oscillators arrays to perform power combining, beam steering, and beam shaping. (more...)

Microfluidic devices are poised to revolutionize environmental, chemical, biological, medical and pharmaceutical detectors and diagnostics. The term “microfluidic devices” loosely describes the new generation of instruments that mix, react, count, fractionate, detect, and characterize samples in a micro-electro-mechanical system (MEMS) circuit manufactured through standard semiconductor lithography techniques. Although a wide array of microfluidic technologies are currently available, novel MEMS fluidic systems are needed as scientists continue to work with smaller sample volumes and desire devices with increased sensitivity and effectiveness. Researchers at the University of California, Irvine have developed a unique non-contact system for sorting monodisperse water-in-oil emulsion droplets in a microfluidic device. The technology can be coupled to other on-chip processes to increase device efficiency by sorting out un-reacted droplets. (more...)

Methods for the preparation of long, dimensionally uniform, metallic nanowires that are removable from the surface on which they are synthesized. The methods include the selective electro-deposition of metal nanowires at step edges present on a stepped surface, such as graphite, from an aqueous solution containing a metal or metal oxide. Where a metal oxide is first deposited, the metal oxide nanowires are reduced via a gas phase reduction at elevated temperatures to metal nanowires. Alternatively, beaded or hybrid nanowires comprising a metal A into which nanoparticles of a metal B have been inserted may be prepared by first electrodepositing nanoparticles of metal B selectively along step edges of a stepped surface, capping these nanoparticles with a molecular layer of an organic ligand, selectively electrodepositing nanowire segments of metal A between nanoparticles of metal B and then heating the surface of the hybrid nanowire under reducing conditions to remove the ligand layer. In all three methods, the nanowires may be removed from the stepped surface by embedding the wires in a polymer film, and then peeling this film containing the embedded wires off of the stepped surface. (more...)

Complex mixtures of aroma compounds are often responsible for the overall aroma of a food, beverage, cosmetic or other product.  Two or more odorants can frequently lead to an aroma that is not similar to any of its components.  A new method and apparatus allow for more precise and informative analysis and characterization of aromas and volatile constituents. (more...)

A novel device and technique for the measurement of the rheological properties of fluid interfaces. (more...)

The diffuse optical spectroscopic imaging (DOSI) device is a tissue spectroscopy instrument designed to measure absorption and scattering properties of tissues. These absorption and scattering spectra are dependent upon the functional and structural composition of the tissue under study. The use of non-ionizing radiation probes the tissues below the surface non-invasively. While the idea of optical tissue spectroscopy is not unique, researchers at the University of California, Irvine have developed a unique compact modular platform that provides high portability yet retains the high information content of spectroscopic imaging of tissues. (more...)

If electricity energy scavenging from vibration became commercially practical, then it would enable large opportunities for powering wireless electronics in many markets -- including, manufacturing, medical care, energy efficiency and personal electronics. However, vibration energy scavengers have been cost-prohibitive and too application-specific. The impediment of application-dependence is due to the fact that vibration energy scavengers only produce useful amounts of power when they are driven at their resonance frequency. Moving even several tenths of a Hz away from resonance frequency has a detrimental impact on power output. Solving this resonance issue is challenging because it's impractical to measure the vibration spectrum at every target location and then customize every vibration scavenger for each location. Furthermore, the vibration frequency at each location can't be expected to remain constant.   To solve this problem, researchers at UC Berkeley have developed a beam-mass system that autonomously adapts its resonance frequency to the ambient vibration frequency, thereby achieving maximum power output in arbitrary vibration environments. The same approach can also be used to autonomously minimize (i.e. de-tune or damp) the vibration amplitude in response to the external input vibration. Whether tuning or de-tuning, this novel system doesn't require any human intervention, control algorithms, or external energy sources (other than the ambient vibration).  (more...)

Dual-beam optical traps, used in conjunction with microfluidic channels, are used for manipulating µm-scale dielectric objects such as biological cells or polystyrene beads. This type of manipulation is helpful for studying the mechanical properties of soft particles and the dynamics of particles suspended in microfluidic flows, and for holding and observing living cells over extended periods of time. However, optical traps/microfluidic systems suitable for practical applications have been quite complicated and expensive to make, primarily due to the difficulties of holding optical fibers in place mechanically on the chip or of using in situ optical wave guides or lasers as substitutes for optical fibers. Of particular concern is the need to incorporate complex microfabricated components into a system’s design to make it compact enough for use with microscopes. (more...)

An FM gyroscope with inherently digital output. Tradeoff between quality factor and range and bandwidth is eliminated, allowing the use of ultra-high Q for improved noise performance without limiting the bandwidth and range. Temperature is self-sensed and self-calibrated, so the hysteresis and lags are eliminated. (more...)

Molecular imaging plays an instrumental role in cancer research, clinical trials and medical practice. Bioluminescence imaging enables the visualization of genetic expression and physiological processes at the molecular level in living tissues by using a bioluminescence reporter, which is usually a genetic transfect from a firefly. This imaging ability opens possibilities for accelerating basic research and drug discovery by allowing in vivo imaging of various disease processes. Currently, the commercial bioluminescence imaging systems developed by Caliper Life Sciences (Xenogen), Kodak and Berthold are for planar imaging and qualitative analyses, and cannot accurately reconstruct a bioluminescent source distribution inside a living animal. Our proposed BLT techniques will allow reliable and accurate analyses on the bioluminescence probe distribution within a living small animal, and offer an excellent instrument to identify disease pathways, clarify mechanisms of action, evaluate efficacy of drug compounds, and monitor their effects on disease progression in animal models. (more...)

Experimenters performing psychophysical studies often give their subjects buttons to press to indicate their responses to questions. The specific patterns in which the buttons are laid out, as well as the number of buttons are typically dependent on the specific experiments. Making button devices compatible with MRI for the purpose of performing functional MRI studies is fraught with multiple challenges and is usually quite expensive. This means that for each new experiment, the investigator may need to spend thousands of dollars to purchase custom made compatible devices. (more...)

The present invention relates to linking devices and displaying their information over a network and, more particularly, a method in which many different devices can upload multiple file types (code, text, audio files, etc.) that can be organized in a manner to be utilized over a network, such as the internet. (more...)

Mass-producible vacuum photon detector without solid metallic electrodes or feedthroughs and with minimized content of radioactive elements, forming arrays without dead area for light detection. (more...)

Diagnostic device for detecting malaria infection by blood sample testing. (more...)

Knowledge of the number of people in a building at a given time is crucial for applications such as emergency response. Researchers at UCI have developed a probabilistic model for predicting the occupancy of a building using networks of people counting sensors. This same model can be applied to detecting unusual variations in any large data set and making useful predictions. (more...)

Power companies have expressed an opportunity for massive numbers of voltage sensors for monitoring high-voltage transmission and distribution lines as well as high-voltage equipment. In addition to monitoring operating status, these massive networks of high-voltage sensors could be used for a variety of novel applications such as monitoring sag as power lines heat-up and monitoring vegetation growth that could lead to arcing fires. However, to implement this vision, the voltage sensors need to be very inexpensive to make, deploy, maintain and operate. To address this opportunity, researchers at UC Berkeley have developed AC sensor solutions for high-voltage applications. These Berkeley AC voltage sensor solutions are MEMS-based for low-cost manufacturing, self-powered for low-cost maintenance, wirelessly networked for easy operation, package for all-weather environments, and they operate by proximity not galvanic coupling -- so they are easy to install. (more...)

A major challenge for the electric power industry is that power distribution cables can fail after years of service resulting in power outages, property damage, severe injuries and costly cable replacement. Furthermore, it has been estimated that simply replacing critical underground power distribution cables in the U.S. would cost many tens of billions of dollars. Consequently, electrical utilities need economical ways to evaluate cables while they are in service (i.e. transmitting electricity). To address this challenge, researchers at UC Berkeley have developed a non-invasive way to probe in-service power cables in order to detect impairments due to damage such as breakage or excessive corrosion of conductors. (more...)

Porous silicon layers prepared to show fine structure in the reflection spectra provide the means to measure the composition of a gas or liquid. Adsorption of molecules in the pores changes the average refractive index of the thin-film and produces a variation in the Fabry-Perot interference fringes. These spectral changes can then be correlated to the pressure of a gas in contact with the sensor. (more...)

This new invention outlines a means of accomplishing underwater time synchronization between arrayed autonomous acoustic recorders without connecting cables between the nodes of the array. Eliminating the wired connections between array elements is seen as providing considerable savings in cost and weight as well as reducing system complexity, improving robustness and portability / reconfigurability. Signal processing schemes are used to maintain timing synchronization between the recorder nodes. (more...)

Using the Tacky Dot®, UC San Diego researchers have adapted the technology to the patterning of carbon nanotubes, nanowires, and other types of nano-materials. This technology places the nanomaterials on the surface of the photopolymer, sandwiched with other materials or in layers to form a structure of nanomaterial. The dry method removes both the need for the use of a flux, which is found in wet methods, and the need to anneal the surface to fix the nanomaterials in place. The method is capable of producing patterns whose size is just a few microns. (more...)

Detecting ultra trace explosive analytes is important for forensic or counterterrorism  applications as well as for personnel, baggage, or cargo screening.  However, metal detectors frequently fail to detect explosives (such as those in the plastic casing of modern land mines); dogs are expensive and difficult to maintain: and other methods, including gas chromatography coupled with mass spectrometry, surface-enhanced Raman, energy dispersive X-ray diffraction, for example, are highly selective, but are expensive and not easily adapted to a small, low-power package.  Therefore, chemical sensors are preferable to other detection devices. (more...)

This invention teaches a low-noise sensor and electronic circuit to measure electrical voltage signals generated by the body without direct contact with the body. The currently available technologies for similar sensors require electrical contact to the skin either with a conductive gel or abrasive skin preparation. This is a non-contact sensor which operates by capacitive coupling and is capable of measuring EEG signals through hair or ECG signals through clothing. In this invention, the circuit senses, amplifies, and acquires the signal from the body. This invention uses a switching device (a transistor or relay) to briefly close a shunting path from the sensing node to the ground potential. The switching mechanism of the circuit offers the advantage of injecting less circuit noise into the critical sensing mode. The target applications are for EEG signals for use in brain-computer interface, ECG for heart monitoring, and EMG for recording muscle activity. (more...)

There is a significant need for more efficient heat transfer techniques in conversion, utilization, and recovery of energy. Traditional techniques used to enhance heat transfer rely on reducing the thermal resistance in a conventional heat exchanger by promoting higher convective heat transfer coefficients. In particular, swirl flow enhancement is popular since secondary recirculation on the axial flow in a channel can be used for single-phase as well as two-phase flows. Twisted-tape inserts are favored due to their ability to increase the heat transfer coefficient, and their ability to carry out tasks at a reduced size. However, twisted-tape inserts pay a sizeable pressure drop penalty during the process. (more...)

Engineers from UC San Diego have developed a patent-pending technology that provides cross-coupled rectifiers that use near zero-threshold transistors in a switching topology that avoids reverse conduction problems. Importantly, preferred embodiment rectifiers of the invention only provide a slightly increased on-resistance in each branch, while providing both very high operating efficiency and very low tum-on voltage. An embodiment of the invention is a voltage rectifier for the conversion of RF energy into DC voltage with a tum-on threshold voltages approaching OV. Whereas traditional CMOS and Schottky diode rectifiers require several hundred millivolts to activate, the present circuit can operate upon near-zero incident energy, enabling a variety of useful applications, including:• Wireless biomedical implants.• Increased range of RFID devices.• Wireless sensors with very low threshold activation.• Reduced complexity of RFID devices while maintaining current performance.• Energy harvesting by converting ambient RF radiation into useable DC power. (more...)

University researchers have designed a new z-axis gyroscope design with a 2-DOF sense mode allowing interchangeable operation in either precision (mode-matched) or robust (wide-bandwidth) modes. This is accomplished using a complete 2-DOF coupled system which, unlike the previous multi-DOF design, allows for the specification of the sense mode resonant frequencies and coupling independent of frequency. (more...)

UC San Diego researchers have developed a new nanotechnology platform called "smart dust" with state-of-the art applications in almost every field of use, ranging from biological sensing and screening to communications technology. The invention utilizes micron-sized particles of silicon that have been etched and then chemically modified in such a way that each individual particle has its own addressable identity. This feature allows one to use thousands of particles together, each with its own tag, for high-sensitivity chemical or biological sensing, diagnostics, and low- and high-throughput screening of biomolecular compounds. The method does not require the use of fluorescent tags, but could be used in conjunction with them. (more...)

Gallium Nitride (GaN) LEDs and laser diodes are currently in use for many applications, but these suffer from several drawbacks. GaN laser diodes emit from the edge, not the surface, which requires bulky structures and advanced engineering to align them in useful orientations.   University of California researchers have developed novel UV ZnO diode lasers on Si that overcomes many of the shortcomings of GaN devices.    ·         UC has developed electrically pumped surface-emitting UV ZnO diode lasers with high output power at 380 nm and low threshold current. ·         UC has developed blue and UV LEDs that can operate at room temperature and very low lasing threshold current density of 10 A/cm2. ·         The new UC devices are made from readily produced materials compatible with current manufacturing techniques ·         Currently UC is working to tune these new materials for UV emission around 280 nm and for high powered green (around 520 nm) laser diodes This figure shows the far-field pattern UC’s laser.   This figure shows the output spectra of UC’s lasers diode at various currents. Note the strong and clean emission in the upper UV wavelengths, centered at 380 nm.     For more information, please contact Eric Tonui at the UC Riverside Office of Technology Commercialization at eric.tonui@ucr.edu  or 951 827 4967.   UC Case Reference Number 2008-670 (more...)

Semiconductor nanowires have been successfully utilized as building blocks for various electronic and photonic devices. In particular, vertically aligned semiconductor nanowire arrays offer the potential of high photoconversion efficiency compared to that of thin film devices given the nanowire properties of enhanced light absorption, improved carrier collection efficiency, and reduced optical reflectance. UC San Diego researchers have developed photovoltaic devices and methods to fabricate said devices that utilize semiconductor nanowires with heterojunction photodiode structures to achieve significant device performance gains, e.g., broad band spectral response and high energy conversion efficiency. Heterojunctions can be formed by direct epitaxial growth of vertically aligned III-V semiconductor nanowire arrays on their substrate, particularly on Si wafer, which allows integration of functional III-V-nanowire structures with CMOS technology. The heterojunction bandstructure therein can be engineered by tuning the III-V alloy composition of the nanowires. For example, heterojunction photodiode devices formed by InAs nanowire arrays on Si substrate have been operated in photovoltaic mode and found to exhibit a visible-to-infrared photocurrent excitation profile. Heterojunctions can also adopt a coaxial or core-shell configuration, i.e., a doped nanowire core surrounded by a shell of complementary doping, with multiple quantum wells and superlattice structures being incorporated between the p-type and n-type regions in certain designs. This geometry enables high optical absorption along the long axis of the nanowires while considerably reducing carrier collection distance in the radial direction. The device fabrication methods include embedding the nanowire arrays in polymer matrices and application of transparent conductors as top electrical contacts. Moreover, the nanowire semiconductor devices can be implemented as high efficiency photoelectrochemical cells to break down water and CO2 for hydrogen generation and CO2 conversion to fuel, respectively. (more...)

Large-scale sequestration of carbon dioxide in underground geological reservoirs is being actively explored as a means to sustain fossil energy use and minimize climate risks. Assuring the integrity of the huge carbon dioxide plume sequestered in such underground reservoirs is central to the viability and acceptability of this approach. It is known that carbon dioxide can leak from underground storage reservoirs. The U.S. Department of Energy has set a limit on carbon dioxide leak rates of 0.01 percent per year to the atmosphere. Detection of carbon dioxide leakage from non-point sources at sequestration sites is problematic because of the variability of carbon dioxide in the atmosphere due to natural ecosystem photosynthesis-respiration fluxes, variations in background air-mass trajectories, and local or regional pollution from fossil fuel combustion. (more...)

A unidirectional gyrotropic photonic crystal allows electromagnetic wave propagation in a certain direction at a certain frequency and at the same time, impedes electromagnetic wave propagation in the opposite direction. The electromagnetic wave with impeded propagation, called the "frozen mode", ideally has zero group velocity and does not transfer the electromagnetic energy. A unidirectional gyrotropic photonic crystal is a periodic composite, incorporating a component displaying Faraday rotation. The property of unidirectionality can be achieved in gyrotropic photonic crystals by proper choices of constituents and their space arrangement. (more...)

Without a distributed amplifier, most broadband amplifier bandwidths can be achieved around 1/10 to 1/3 of their fT only. Therefore, a high bandwidth amplifier requires high fT (at least 3-10 times of the amplifier bandwidth) transistors in order to achieve high bandwidth. Unfortunately, the current device technology is limited and in very high fT transistors, yield is still low. This leads to high cost and low yield.Even if high gain-bandwidth product could be achieved by a distributed amplifier, the major disadvantages of the distributed amplifier are large area, and high dc power consumption. Transistors were operated with high current density for high fT in order to achieve high bandwidth amplification. However, the transistors would become highly stressed resulting in reliability problems and short lifetimes. 50 ohm terminations are currently employed at the input and output of broadband amplifiers in order to obtain desirable input and output broadband impedance matches (low S11 and S22). However, the disadvantage is 3-dB losses at theirs inputs and outputs. (more...)

Piezoresistive accelerometers are traditionally fabricated by doping selected areas of wafer to achieve isolated pn-junctions. Often, two separate doping steps are employed to obtain both highly-doped conductors as well as lightly-doped piezoresistors. Once the piezoresistors and conductors have been defined, additional fabrication steps are required to etch the suspension system as well as the free-standing proof mass, which normally deflects in the out-of-plane direction.Normally, four or more masks are used in the fabrication process making for complex and costly manufacturing. In addition, pn-junctions have high leakage currents at temperatures above 150OC, which is therefore the highest operational temperature of the sensors. (more...)

Large scale confinement chambers have been created in the past using traditional glass-blowing techniques. However, conventional glass-blowing can only be used to create large components and requires the components to be made one at a time. Micro-glass spheres have previously been fabricated by letting glass particles fall through a temperature-controlled drop tower. While it is possible to create hollow spheres by introducing a blowing agent in the glass, these micro-spheres are not attached to a substrate and are therefore difficult to integrate with micro-machined components on a wafer. (more...)

Microelectrical-mechanical systems (MEMS) are miniature mechanical devices intended to perform non-electronic functions such as sensing or actuation. These devices are typically built from silicon using lithographic techniques borrowed from the semiconductor industry. This manufacturing technique is expensive and limited. Furthermore, almost all micromachined devices must eventually be placed in a protective housing so that electrical connections can be made to the devices, and to protect the devices. This is troublesome for MEMS devices because they are fragile and so extreme care must be taken to move them from their fabricated substrates (e.g., wafers) to micro-electronic packages. It is well known that 60%-80% of the final cost for a MEMS device is from the costs associated with packaging. (more...)

SPI is one of the most popular bus interfaces between a microcontroller and a peripheral device. However, system designers often overlook a bottleneck, which uses SPI inefficiently when transferring between two slave devices. Our technique eliminates this bottleneck with very simple hardware, and this should be of interest to manufacturers of microcontrollers. Peripheral devices would not require any modifications and can be used just as before. (more...)

Researchers at the University of California, Berkeley have developed a new micro-machined device which measures directly the angle of rotation, in contrast with any conventional micro-machined gyroscope that measures the rate of rotation. Integrated on a single silicon chip, this unique micro-gyroscope is based on inertial properties of elastic waves. (more...)

Design and fabrication of micromachined resonant scanners that have large scan angles at fast scan speeds. Driven by an electrostatic comb motor, these 200-micron scanning-micromirros can scan about 12 optical degrees at the resonance frequency of 3 kHz with a sinusoidal voltage input of 20 V in amplitude. Fabricated with a 4-poly-layer silicon-surface-micromaching process, they are compact, light in weight, low-consumption and low-cost. A bar code reader prototype has been demonstrated as a potentially important application. (more...)

Researchers at the University of California, Berkeley have developed a non-invasive method of determining the position and condition of reinforcing steel embedded in concrete. Electrodes are use to carry out the method by contacting the outer surface of the concrete. The method measures the impedance of selected regions of the concrete by measuring the voltage generated across said selected regions by a current flowing through the concrete. (more...)

In order to improve energy efficiency and correspondingly lower energy use and cost, there is growing interest in improving the intelligence of electricity usage across the grid – including down to the level of common electronic devices that use single wire or two-wire “zip-cord”. To enable this ubiquitous level of intelligent electricity usage, AC current sensors will be needed that are inexpensive to make, simple to install, and easy to maintain. However AC current sensors with these attributes have not been developed. To address this challenge, researchers at UC Berkeley have developed an integrated sensor device that can measure AC electric current in a wire or wires that are operating in proximity to the device without requiring (1) electrical contact with, or physical encirclement of the conductors, or (2) precise spatial orientation or precise physical mounting/placement of the sensor device relative to the conductors. These attributes make the sensor inexpensive to manufacture, easy to install and simple to maintain. (more...)

By 2010, more than 10% of the MEMS market will be devoted to harsh environment sensors. Embedded sensors have increasingly become more popular among the industries that require accurate monitoring of the current phenomena in their physical systems. A range of physical conditions such as variable temperature, fluctuating pressure and external forces induce internal stresses and strains which may lead to fatigue, brittle failure, plastic and permanent deformations in a solid. Because sensors must be placed as closely as possible to the incident in order to provide accurate readout, they are exposed to harsh and aggressive environmental constraints, which can alter their resolution and accuracy. Current sensor technology includes piezoresistive gauges, surface acoustic wave sensors and fiber Bragg-grating strain sensors. However, each of these technologies has serious limitations like material degradation when exposed to humidity, temperature sensitivity, and dependence on bulky light sources and electronics for output readout. To address these problems, Researchers at UC Berkeley have developed a high-resolution sensor, which can continuously measure the strain in substrate under aggressive environments such as extreme temperature, corrosive media and high-g shocks. It has a sub-millimeter gauge length capable of precise assessment of strain fields. The device has a novel structural design which performs as a function generator to magnify the applied strain in the desired direction while attenuating the cross-axis strain effect to less than 10% of the readout signal. (more...)

In order to improve energy efficiency and correspondingly lower energy use and cost, there is growing interest in improving the intelligence of the electricity utilization across the grid from appliance cords, to the distribution cables, to transmission lines. This smart grid will require ubiquitous sensors that are inexpensive to make, simple to install, easy to maintain – however voltage sensors with these attributes haven't been developed. To address this challenge, researchers at UC Berkeley have developed MEMS-based measurement systems that can detect voltages using three approaches. One approach is optimized for appliance cords, another approach is optimized for distribution cables (with voltages from 4 kV rms to 35 kV rms), and the third approach is optimized for transmission lines. All the approaches use wireless technology to transmit measurements, and all the measurement systems are inexpensive, small and rugged. Furthermore, the systems for appliance cords and distribution cables can scavenge and store energy to power the sensors and transceivers. (more...)

Computer-based recognition of human physical actions is gaining attention in fields such as medical care, tele-immersion and athletic training. Most conventional approaches to computer-based recognition of human actions are based on computer vision systems along with model-based or appearance-based vision algorithms. However, these conventional approaches have limitations including the requirement for human subjects to be observed in a finite environment that is instrumented with cameras and other sensors -- and those instruments can't analyze very small body movements. To address this problem, researchers at UC Berkeley have developed a distributed recognition framework to segment and classify human actions that was inspired by emerging compression sensing theory. (more...)

New medical systems are needed to weather the storm of rising healthcare costs. In particular, Point-of-Care (POC) technologies have the potential to keep costs at bay by enabling affordable preventative diagnostics and personal chronic disease monitoring. Many of these POC technologies use detection schemes that rely on the specific marking of target analyte with labels, such as catalytic enzymes, optical markers or magnetic beads. The latter are very useful as labels for bio-assay applications because a) cells exhibit few if any magnetic properties, b) signals from magnetic beads are stable with time, c) magnetic detection functions regardless of the opacity of the sample, and d) magnetic labeling provides added functionality such as magnetic filtration and manipulation. Integrated detection of magnetic beads has been demonstrated using MR spin valves. Researchers at the University of California have developed a fully integrated system capable of detecting single super-paramagnetic beads using CMOS. The system greatly simplifies detection protocol complexity and reduces overall system cost. (more...)

Cantilevers are commonly used in MEMS as simple sensor elements for transducing environmental stimuli. However, a key challenge in commercializing these cantilevers is the readout design. The traditional readout approach is nontrivial as each element needs to be addressable and the readouts generally require either an optical setup or a custom circuit attached to each cantilever. The optical approach typically uses large, remote, expensive technology to input light and measure the reflection. The circuit approach must be integrated with the MEMS fabrication process and interfaced into an array. To address these cantilever readout challenges, researchers at UC Berkeley have developed several readout designs that maximize the sensitivity of the sense array, without sacrificing available space for the sense electronics. In addition to minimized space requirements, these readout designs each have advantages such as improved noise suppression / cancellation. (more...)

Phase-shifting interferometers are optical phase sensors that can be used to measure fast, transient phenomena. However their commercial use has been limited due to their relatively high costs and the speed limitations on what these devices can measure. Conventional MEMS-based interferometers are costly because their parts are fabricated on separate wafers and then need to be assembled as well as aligned -- which are relatively slow, expensive, low yield steps. Moreover, some existing interferometer designs require a high temperature annealing fabrication step, and that heat is problematic for integrating electronic components. In order to broaden the market opportunities for high-speed interferometers, researchers at UC Berkeley have developed a new MEMS-based interferometer design. In comparison to previous interferometers, this design can measure faster phenomena as well as enter more cost-constrained and portable markets. With it simpler and higher yield fabrication process, this micro-machine, batch processed interferometer is expected to be 10-times less expensive than previous designs. The Berkeley research team has fabricated prototypes of this interferometer that can make 20 to 30 measurements per second, and has conducted tests in which the device has continuously capture more than 500 profile measurements of a transient phenomenon over 21.7 seconds. (more...)

Patterning of biomolecules is important in areas like biological analysis, diagnostics and genomics. In addition, molecular patterning could be useful for spatial control of various surface properties such as hydrophobicity and surface charge. Currently, molecules are patterned using lithography, stamping, or using scanning tips. Lithography requires either specially synthesized light-sensitive molecules or exposure to developing solutions for photoresists, which are usually incompatible with sensitive molecules. The other two processes involve a mechanical transfer of molecules between a stamp or a scanning tip and the surface to be patterned and are therefore highly sensitive to surface tension, transport on the tip and other surface phenomena. These techniques also require specialized scanning tips or alignment equipment. While these techniques are useful for patterning two-dimensional patterns on surfaces with sub-micron resolution, no technique exists for patterning within confined regions such as small microchannels or nanochannels. Researchers at UC Berkeley have developed a new technique for patterning molecules that is compatible with sensitive molecules and can be used in confined areas. The process can be used for applications in microfluidics and nanofluidics, where patterning using other techniques is not possible. The method is also useful for patterning of surface properties such as surface charge. Other applications include patterning biomolecules such as antibodies inside of nanopipettes and patterning sensitive biomolecules on flat surfaces. (more...)

The field of infrared detection is well established with many applications and associated design variations. IR sensors requiring high sensitivity typically need to be cooled to ultra low temperatures -- adding to their complexity and consequently making them more costly or unsuitable for ambient temperature applications. To address this limitation, researchers at UC Berkeley, using a biomimetic approach, have developed a new type of IR detector that combines a modified strain gauge with an organic material for IR transduction. Infrared radiation incident on the organic material modulates a displacement of the material in order to detect the presence and intensity of IR radiation. This innovative design doesn't require cooling, and is sensitive to 9 and 3 ?m -- wavelengths that are emitted by mammals and forest fires, respectively. (more...)

Conventional flow cytometry has made valuable contributions to cancer diagnosis and management as well as to the understanding of fundamental cancer cell biology. Flow cytometry is used routinely in the clinical diagnosis of the hematologic malignancies; in tumor immunology to define lymphocyte subsets; and in basic research to facilitate cell separations based on the expression of particular proteins or phospholipids at the cell-surface. However, it does require a large sample of cells and usually requires labeling. Researchers at the University of California, Berkeley have developed a new approach to flow cytometry; the researchers call it "NanoCytomerty." The novel technology uses an integrated microfluidic chip which can adapt to sort cancer and other types of cells based on their cell-surface protein expression. The technology allows for significant improvements over conventional flow cytometry, because the system permits label free signal detection, extreme reproducibility and sensitivity, and cell separations using very few cells. By developing a more sensitive technique to perform cell separations, in addition to one that relies on fewer cells, we anticipate that NanoCytometry could provide an important new technology applicable to cancer. For instance, NanoCytometry could be used to improve upon physicians' ability to detect minimal residual disease states and upon a scientist's ability to study cell populations that occur in very small numbers such as stem cells. Nanocytometry builds upon previous work which includes an all-electronic technique for detecting the binding of unlabeled antibody-antigen pairs (US Patent Appl. # 10/056,103). (more...)

Piezoelectric bending actuators have the potential to be used as the muscles in a variety of autonomous, micro-mechanical robotics devices under development. While commercially available bending actuators have the requisite high levels of mechanical energy for these miniature robotics applications, the mass of these existing actuators are too high -- by orders of magnitude. To address this problem, researchers at UC Berkeley have developed a new class of piezoelectric bending actuators with ultra-high energy densities. These new actuators have been optimized for low-mass applications using sophisticated math models, and their benefits are based a variety of innovative design features and fabrication methods. The actuators can be tailored for most kinematic and dynamic requirements. Whereas commercial piezoelectric bending actuators have energy densities that range from 0.15 to 0.007 Jkg(-1), and masses that range from 340 to 120,00 mg, a bimorph version of this new class of actuators exhibited an energy density of 2.5 Jkg(-1) with a mass of just 11 mg. (more...)

Commercially available optical tweezers can move objects using laser light, but they are generally not used to measure forces exerted on those objects, since accurate force calibration is difficult. Research in the field of optical trapping has led to the development of optical tweezers that measure forces (transverse to optic axis) by changes in light-momentum. Force calibration is greatly simplified by using this method. However, in measuring the light force on a trapped object, it is also desirable to obtain all three vector components of that force. Representing an improvement on the light-momentum force-sensor, researchers at the University of California, Berkeley have developed an axial light-force sensor. A system incorporating the Berkeley improvement permits simultaneous measurements of the axial and transverse forces acting on a trapped particle. Like the transverse sensor, the axial force sensor is calibrated from measured constant values: the speed of light, the objective focal length, and the power sensitivity of the planar photo-diode. Thus calibration is not affected by particle shape, laser power, particle refractive index, or sharpness of the trap focus. In addition, a highly-miniaturized, ultra stable, optical trap system has been developed that should permit a low cost instrument with force-measuring capabilities for use in normal lab environments. (more...)

Electrostatic comb-drives are used to make torsional actuators in numerous MEMS applications. However, the linkage- and hinge-designs of these actuators have reliability problems and limit maximum operation frequencies. Furthermore, existing designs are difficult to fabricate because the comb structures are challenging to align, or require elaborate wafer bonding, grinding, polishing and silicon anisotropic-etching processes. To improve the performance and simplify the fabrication of torsion-bar microactuators, researchers at UC Berkeley have developed torsional actuators that are made using self-aligned plastic deformation in a batch process. The microactuators are formed in simple, rugged single-crystal silicon and driven by vertical comb drives. The batch process is controllable, repeatable and does not include any critical alignment steps. Using this design, MEMS scanning mirrors have been built that resonate at frequencies between 1.90 and 5.33KHz achieving scanning angles up to 19.2 degrees with driving voltages of 40Vdc plus 13Vac. After more that 5 billion cycles of continuous testing at the maximum scanning angle, the plastically deformed silicon torsion bars have not exhibited any degradation or fatigue. (more...)

Using micromachined gyroscopes to measure angular velocity is becoming increasingly common in applications ranging from ballistics and crash-testing to mobile micro-robotics. Although a variety of MEMS gyroscopes are commercially available, their dynamic range, power requirements and package size are sometimes not well-suited to the applications. To address these problems, researchers at the University of California at Berkeley have developed a radically new type of angular rate sensor. Based on the biological mechanism of flying insects, this Berkeley biomimetic gyroscope uses piezoelectric actuators to measure angular velocity. There are several advantages to using this biomimetic approach over MEMS-based designs. First, the biomimetic gyroscope has a much greater dynamic range. It can detect angular velocities from as low as tens of degrees per second to as high as hundreds of thousands of degrees per second -- three orders of magnitude higher than most MEMS gyroscopes. Second, in applications involving rapidly moving objects, this Berkeley gyroscope requires much less power than the MEMS alternatives. (more...)

A new portable observational truss, capable of retrieving water, soil, air and weather measurements in harsh conditions, has been developed by researchers at the University of California, Davis. Utilizing a stable tripod design and a sampling arm capable of full rotation, this novel construction allows for sample retrieval and instrument placement in otherwise inaccessible locations. These locations may include geographic sites such as mountain rivers, volcanic lakes, fumaroles and hot springs, as well as any foreseeable industrial site where liquids and gases need to be measured. Images River Truss (more...)

Current gyroscope feedback control and signal processing elements take the form of a discrete analog implementation and/or a general purpose digital signal processing (DSP) chip. However, both of these methods present drawbacks. The discrete analog option is inflexible with regard to modifying component values for the purpose of "tuning" or customizing the control loops for a given sensor. The chip's disadvantage is that general purpose DSPs do not lend themselves to applications that require low power consumption, such as in spacecraft and mobile systems. (more...)

Micromachining of axisymmetric silicon resonators for gyroscopes using DRIE leaves a fixed residual resonant frequency mismatch of 1 to 0.1 HZ for mesoscale resonators and 10 to 30 Hz for millimeter-scale microgyro resonators. Current methods do not allows any adjustments in-situ and are difficult to apply to an assembled gyroscope. Gyroscope quadrature drift is proportional to frequency mismatch and for navigation-grade applications high-Q resonators with mill- or micro-Hz matching of kHz resonances are desired. Laser-assisted gas etching or laser ablation after micromaching has been attempted, but it is unprecise and gas reaction products or debris may damage the resonator or assemble gyroscope. Electrostatic bias trimming can be used to adjust one or more resonance frequencies for some resonators, such as capacitive gyroscopes. However, this method is subject to electrical errors and thermal tracking of mechanical and electrical errors. (more...)

Scientists at the University of California have developed an inexpensive quantum dot infrared detector with a dramatically improved signal-to-noise ratio and thus greater sensitivity. The device upconverts the energy of infrared photons in the 50 meV to 200 meV range (corresponding to wavelengths from 6 to 250 microns) yielding infrared photons of higher energy. These higher energy photons can be easily imaged with a Si CCD camera. An ultimate resolution of 50 nm can be achieved in the imaging mode using a near-field scanning optical microscope for reading the upconverted image. (more...)