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...)

University of California researchers have developed an optimized mixture of graphene and multilayer graphene that utilizes high-yield liquid phase exfoliation techniques to significantly increase the thermal conductivity of thermal interface materials.  While current thermal interface materials have thermal conductivity values in the range of ~1 to 5 W/mK at room temperature, University of California researchers have achieved thermal conductivity values at or above 25 W/mK at room temperature with only small graphene loading fractions at 5% by volume.  The graphene and few layer graphene are utilized as filler materials with various base (or matrix) materials to form the thermal interface materials.   (more...)

Thermoelectric devices are made from rigid bulk or bulk like material which are inherently inflexible. Alternative thermoelectric device designs which incorporate semiconducting nanowires are able to be rigid and yet be flexible.   For example, despite the rigidity of semiconducting nanowires they can move independently from each other, enabling flexible thermoelectric device designs. The use of rigid or semi-rigid electrodes for flexible thermoelectric devices causes many difficulties including but not limited to stiffening the device, creating stresses in the active material contacts, and fracturing the active material and contacts. Flexible metallic materials are essential in developing thermoelectric device as envisioned by UCSC researchers.   (more...)

Currently, optical microcavity fabrication methods using nanowires require multiple material depositions and additional fabrication steps including precision alignment of the randomly placed nanowires. Further, such microcavities are relatively inefficient at trapping light and consequently require a threshold power of a factor of 1000 or more. Although there are lasers such as the vertical cavity surface emitting lasers (VCSELs) and "top-down" photonic-crystal lasers with higher performance measures, they require the use of thick semiconductor films and thus cannot be incorporated onto integrated circuits without extensive and low yield process steps. (more...)

Researchers at University of California, Davis have developed a cost effective and miniaturized device that can determine the size of particles in suspension with a precision better than 10nm. (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...)

Researchers from the UC Davis Biomedical Engineering department have developed an innovative microdevice packaging process which enable capillary-driven micron-scale self-alignment and universal nanopatternable interfacial bonding, without incurring thermal or electrical barriers. (more...)

Photolithography, an essential process in the fabrication of integrated circuits, has undergone continuous advancements that allow patterning of nanometer sized features. For example, features as small as 50 nm can be made by using excimer lasers with wavelengths of 248 nm and 193 nm (i.e., deep ultraviolet light). However, it is not always feasible for scientists to use the short wavelength lasers because they are expensive. A method that allows for high resolution photolithography without large capital expenses will be very useful. Researchers at the University of California, Irvine have developed a photolithography method that allows for high resolution patterning. By using this method, one can get a 20-fold improvement in the limit of resolution in comparison to the inherent resolution of “top-down” processing. In addition, the method is easy to use, inexpensive, and does not require sophisticated instrumentation. (more...)

A major limiting factor today for high-resolution, three-dimensional patterning of polymers and nanoparticles in large area, high rate methods is the templates for molding the materials. Currently, only poly(dimethylsiloxane) (PDMS) has sufficient vapor permeability to accomplish this, and the low modulus of elasticity of this material limits the attainable resolution, alignment, and structural fidelity. To address this challenge, investigators at the University of California have developed a highly rigid, chemically robust, optically transparent and vapor-permeable poly(4-methyl-2-pentyne) template. Normally used in gas separation applications, the investigators have nano-patterned this material to create a template. The template has successfully patterned polymers and nanoparticles using the microfluidic molding technique, with very high fidelity pattern replication. Using this mold material, a resolution of better than 350 nm was achieved to date. Patterns resemble those obtainable with photolithographic methods, with as-designed dimensions, completely straight sides and vertical sidewalls. This material substantially extends the capabilities of soft lithographic processes through its increased rigidity and vapor-permeability. Additionally, the properties of this polymer are ideal for roll-to-roll patterning of polymers and nanoparticles for electronics applications. (more...)

Lighting is a major contributor to electricity consumption, accounting for 19 percent of global use and 34 percent in the U.S. The U.S. lighting market is currently dominated by the incandescent light bulb and is only 5percent efficient whereas the fluorescent lamp is 15 to 25 percent efficient. Compact fluorescent lamps (CFLs) have a rated lifespan of 6,000 to 15,000 hours whereas incandescent bulbs have a lifespan of only 750 to 1,000 hours. On the other hand, CFLs contain small amounts of mercury, a neurotoxin, which gets released with breakage. Solid-state luminaires, which are typically based on light-emitting diodes (LEDs), have the potential to revolutionize the industry with higher efficiency, lower maintenance, and better quality/safety, possibly leading to a reduction by half of energy consumed by general illumination. (more...)

One-dimensional nanostructures such as semiconductor nanowires and carbon nanotube arrays have been shown to possess exciting electrical, optical, and mechanical properties. While many of these nanostructures have been made into discrete prototype devices, volume manufacturing is not yet feasible. (more...)

Researchers at the University of California, Irvine have developed a novel method to continuously pattern nanofibers on 2D and 3D substrates. A unique polymer ink formulation provides the right balance of viscosity and elasticity necessary to enable controlled, seamless near-field electrospinning of nanofibers at very low voltages. (more...)

Technological advancement demands new types of transducer materials that can efficiently sense and convert force and energy form one type to another for signal processing and modulation, switching and actuation, sensing and energy harvesting. It is also desirable to have transducer materials that mimic cylindrical outer hair cells and retinal cells and able to detect and convert signals instantly and reliably with exceptionally high coupling efficiency at reduced size. Nanocomposite materials could provide the necessary advantages, but are difficulty to be synthesized with controlled morphology and interface characteristics. The rod-coil copolymer systems have attracted widespread interest in both fundamental understanding of the thermodynamics that control nanoscale self-assembly in polymers, as well as technological implication associated with the unique characteristics of the novel designed systems. With inception of the responsive polymer system designed by the inventors, for the first time, there are opportunities to design materials without the compromises typically found in conventional composites. The rationally synthesized nanomaterials can be processed in a thin film format, which provides a platform for technology innovation. (more...)

Enzyme-based logic gates and their networks are recent developments in the field of biochemical information processing or biocomputing. Chemical logic gates mimic Boolean logic operations and are composed of chemical systems where the input and output signals are represented by concentrations of reactants and products, respectively. In particular, enzyme-based logic gates perform enzyme-biocatalyzed reactions resembling properties of Boolean logic systems. (more...)

In electron beam lithography (EBL), after developing, the cross section of the resist has a parabolic undercut with a linewidth determined by the exposure in the top resist layer resulting in a typical linewidth of 100nm. (more...)

Film bulk acoustic wave resonators (FBARs) have been successfully commercialized in wireless front-end architecture as filters and duplexers. Similarly, silicon micromachined resonators have demonstrated excellent fQ values. Such devices have entered the market at HF and VHF ranges but several obstacles need to be overcome for capacitive resonators can be used at UHF frequencies. (more...)

Currently, thermo-photovoltaic (TPV) cells are based on traditional semiconductor thin-film technology. For a radiation source with a temperature of 1500K, the efficiency of the cell is ~20% during operation at room temperature. However, efficiency decreases greatly with increasing cell temperature. With regards to power conversion in space, it is also difficult to obtain efficiency over 30% when the cell temperature is 400K. Still, TPVs are of great commercial interest. (more...)

Flexible and transparent transistors have recently resulted in several noteworthy achievements. Transparent transistors have been fabricated using both polymers and inorganic oxides. Both have significant deficiencies, however. Polymers have low mobility and inorganic oxides do not have the desired flexibility and simplicity in manufacture. In current transistor configurations, the gate and also the source and drain are metal electrodes, and thus are neither flexible nor transparent. In addition there is usually a large interface resistance between the electrodes and the carbon nanotubes network. Furthermore, there is a need for a simple method of fabrication, where the different layers that form the transistors and the fabrication of the different layers are compatible. (more...)

Currently, optical monitoring is all that is available to monitor undercut etch rates.  This method has limitations, as it is not possible to fully measure the remaining material to be etched.  Also, this approached makes automation difficult. To meet this challenge, investigators and University of California at Berkeley have developed a method where undercut etch rates can be characterized using purely electrical means.   Beams of different widths are undercut by an etchant.  Conducting beams are fully undercut when all the material beneath is removed.  The fully undercut beams are made to collapse into contact with another conducting "landing" electrode by way of surface tension.  By observing the widths of beams which are collapsed, undercut etch rates are measured.  By alternating the semiconductor doping type of the beam and the landing electrode, diodes may be formed, making sensing of etch rates possible in an addressed array. (more...)

With the advent of implantable medical devices, such as pacemakers, defibulators, and insulin pumps, among others, there has been an ongoing need to provide a safe and compact energy source. Nuclear power, electrical batteries, and chemical sources, such as physiologic sugars, have been used and investigated. Classically, a titanium "can" has been employed to contain the electrical components and battery, to avoid the corrosive effects of body fluids. With the advent of implantable electronics and computer chips, this partially advantageous application is limited by lack of effect availability of an energy source. Investigators at University of California have developed the nanogenerator that can be used for new self-powered nanodevices that harvest electricity from the environment for applications such as implantable biomedical devices, wireless sensors, and portable electronics. This innovation is particularly advantageous for implantable medical devices. This nanogenerator innovation provides for self-powered devices. The nanogenerator can be employed to trickle-feed energy to a battery for higher energy needs, such as implantable defibulators. In this invention, piezoelectric poly(vinylidene fluoride) (PVDF) nanofibers are directly written and polarized simultaneously onto the plastic substrate as nanogenerator using near-field electrospinning (NFES). Repeated and consistent output voltage up to 8.5mV has been generated by the nanogenerator under an external strain of 0.092% from a single PVDF nanofiber, of which the output power would be -7.2 pW. (more...)

University researchers have invented a low-cost, high performance, and substrate independent RF MEMS technology for RF MEMS switch fabrication with high yield and reliability. It is compatible with well established printed circuit board (PCB) technology and allows the choice of any substrate with desired electrical and mechanical properties for a specific communication application, to enhance its performance and reduce cost. (more...)

The development of multifunctional, high throughput lab-on-a-chip depends heavily on the ability to measure flow rate and perform quantitative analysis of fluids in minute volumes. Traditionally, there have been many microelectromechanical system (MEMS) based flow sensors for gaseous flows. In recent times, there is some advancement in measuring micro flows of liquids. Examples of sensing principles explored in the measurement of microfluidic flow are heat transfer detection molecular sensing, atomic emission detection, streaming potential measurements, electrical impedance tomography, ion-selective field-effect transitor and periodic flapping motion detection. Flow sensors based on sensing the temperature difference require a complicated design and the integration of the heater, temperature sensors and membrane shielding is difficult to implement. Most other methods are not capable of measuring very low flow rates. (more...)

Capacitive detection and actuation are commonly used in micromachined devices due to simplicity of implementation and effectiveness. However, the performance of capacitive sensors and actuators highly depends on the nominal capacitance of the microsystem. For example, in capacitive micromachined inertial sensors (i.e. accelerometers, gyroscopes, etc.) the performance is generally defined by the nominal capacitance of the sensing electrodes. Furthermore, in electrostatically actuated devices, the nominal actuation capacitance determines the required drive voltages. For a small actuation capacitance, large voltages are needed to achieve sufficient forces, which in turn results in a large drive signal feed-through. Thus, it is desired to maximize the sensing capacitance, and minimize the actuation voltages by increasing the actuation capacitance. However, the sensing and actuation capacitances of micromachined devices are limited by the minimum-gap requirement of the fabrication process. (more...)

Recent attention has focused on high aspect ratio carbon micro-electromechanical (C-MEMS) because of the many applications possible, such as micro-electrodes in electromechanical sensors and miniaturized energy storage/energy conversion devices. Further, suspended micro/nano carbon structures exhibit a wide electrochemical stability window which makes them interesting for integration in mechanical, electrical, and electromechanical measurements. One of the biggest advantages of suspended micro/nano carbon structures is the high surface to volume ratio.Yet, microfabrication of C-MEMS structures using current processing technology, such as focus ion beam (FIB) and reactive ion etching (RIE) tends to be time consuming and expensive. Low feature resolution, and poor repeatability of the carbon composition as well as the widely varying properties of the resulting devices limits the application of screen printing of commercial carbon inks for C-MEMS. (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...)

SEVERAL important classes of MEMS devices, such as resonators, gyroscopes, and chemical sensors, rely on resonance phenomenon in their operation. In these devices, resonant motion needs to be actuated, sensed, and controlled. Capacitive phenomena are commonly used for transduction in vibratory MEMS devices due to the ease of fabrication, low sensitivity to temperature changes, and other practical advantages. However, conventional capacitive detection schemes produce a signal proportional to such system parameters as nominal sense capacitance, carrier voltage, and gain of the current amplifier. These dependencies constitute a need to calibrate individual MEMS devices to address fabrication imperfections, and fluctuation of the parameters due to changing environment and aging. A detection technique independent of these system parameters can be of great advantage. (more...)

Magnetometers are used for sensing magnetic fields. Applications include geophysical surveying, nuclear magnetic resonance imaging (MRI), magneto-encephalography and perimeter surveillance. Gyroscopes sense rotation. Together, these instruments are used in inertial navigation and platform stabilization such as anti-roll systems in cars. A variety of commercial magnetometers exist with various application areas. Superconducting quantum interference devices (SQUIDS) are highly sensitive but require cryogenic cooling. Atomic magnetometers are even more sensitive but run approximately $10,000 per unit. Commercially available gyroscopes run a similar gamut. (more...)

Photolithography is the most widely used micro-fabrication technique as it is a parallel, cost effective, and high throughput process. However, conventional photolithography techniques have a resolution limit that is about half of the illumination light wavelength in free space. To date, various approaches to improve photolithography resolution have developed, but each is flawed. For example, electron-beam lithography, focused ion-beam lithography and dip-pen lithography are slow series processes not suitable for large-area pattern fabrication, and implementing reduced wavelength illumination drastically increases instrument complexity and cost. To address these problems, Researchers at UC Berkeley have developed a family of deep-subwavelength photolithography technologies. These novel technologies are based on adding an artificial metal-dielectric structure to conventional photolithography processes to fabricate reduced patterns of the conventional photolithography masks. The technique overcomes the resolution limit of the conventional photolithography and can achieve deep-subwavelength resolution comparable to that of plasmonic nanolithography and near field contact photolithography. Furthermore, it can fabricate large-area uniform patterns while plasmonic nanolithography can not. (more...)

Quantum dots show great potential for use in next generation optical devices, including photodetection in sensing applications, due to their third order optical response and fast response times. To achieve stability and processability with these nanoparticles, it is ideal to incorporate them into a polymer matrix forming a hybrid material, commonly known as nanocomposites. However, patterning these nanoparticles into nanocomposites is challenging. To address this challenge, researchers at UC Berkeley have developed a novel approach and method for patterning nanocomposites. Using this new Berkeley approach, a nanocomposite film can be patterned and incorporated into a transistor structure in which the film acts as a semiconducting active layer. Additionally, with optical stimulation matching the absorption spectrum of the nanoparticles, the resulting photoconduction can be optimized to create a novel, polymer, transistor-based photodetector. Unlike previous nanocomposite transistors, this new design is simpler to fabricate and uses readily available, inexpensive materials. (more...)

Technological advances have allowed computer microprocessors to handle data at an extraordinary rate. However, the electrical interconnects within and between microprocessor chips introduce a severe bottle-neck to the flow of data. A promising architecture for next generation interconnects is high-speed and high-bandwidth optical interconnects, which will require heterogeneous integration of compound semiconductors with Si technologies. Some previously-explored methods for creating the optoelectronic circuitry include epitaxial growth, heteroepitaxial growth, and wafer-bonding. However, epitaxial growth of interconnections can produce large physical mismatches between desirable compound semiconductors and silicon; heteroepitaxial growth is complicated, expensive, and requires high processing temperatures that damage silicon-based circuitry; and wafer bonding is extremely susceptible to misalignments. Researchers at the University of California, Berkeley are developing advanced structures and methods for integration of compound semiconductors with conventional integrated circuit components to produce various active and passive optoelectronic components for optical interconnects, sensors, semiconductor lasers and other devices. The structures can accommodate quantum wells or quantum dots. The method under development at Berkeley will eliminate problems with alignment and processing temperature that constrain the application of conventional methods for fabricating optoelectronic circuitry. (more...)

  As semiconductor devices are scaled into the sub 50 nm regime, short-channel effects and poor subthreshold characteristics begin to be problematic for traditional planar transistors. Novel device geometries with enhanced performance, defined by functional density, energy efficiency, scalability, compatibility with CMOS, are required in order to push toward ever higher packing densities in memories and logic chips with ever increasing energy efficiency.   University of California investigators have addressed this challenge by providing vertical silicon nanowire array growth with tight control over size «20 nm), uniformity (± 10%), position (allow addressability), density (106_1012 cm·; scalability), and precise doping.  They have demonstrated the first silicon nanowire vertical surrounding gate transistor (Si-NW -SGT). This technology provides the possibility of integrating Si nanowire vertical surrounding gate transistors into arrays and stacks for memory and logic technologies. In contrast to currently available mentioned, the investigators approach relies on a bottom-up process to produce the precisely defined "channel" (epitaxial silicon nanowire vertical array) of the proposed surrounding gate transistors. This vertical geometry also readily differentiates from the previous work on nanowire transistors, all of which adopt a lateral device geometry. Using directed colloid seeding for VLS-CVD SiNW synthesis provides precise control over nanowire diameter, growth density, and spatial distribution. At the same time, the SiCl4 precursor is highly effective for the growth of vertically aligned, single-crystalline SiNWs. Moreover, these techniques facilitate the direct integration of nanowires into complex systems such as microfluidic devices. The versatility of these growth control methods stems from the use of SiCl4 as the gas phase precursor. Link to PCT patent application (more...)

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The objective of molecular imprinting is to create solid materials containing chemical functionalities that are spatially organized by interactions with imprint (or template) molecules during the synthesis process. Subsequent removal of the imprint molecules leaves behind designed sites for the recognition of small molecules, making the material ideally suited for applications such as separations, chemical sensing and catalysis. A significant limitation to the use of bulk imprinted silica in catalytic applications has been due to the hydrophobic framework resulting from the materials synthesis process. Researchers at the University of California, Berkeley have developed a process for synthesizing a new class of bulk imprinted silicates with a hydrophilic framework, which circumvents these limitations. Imprinted sites consisting of up to two primary amines have been synthesized within hydrophilic microporous and mesoporous inorganic-oxide frameworks. The preparation of bulk-imprinted silicas is a step toward the development of imprinting as a general strategy for synthesizing materials-by-design. (more...)

Researchers at the University of California, Berkeley have developed highly sensitive ultraviolet light sensors based on zinc oxide nanowires. Upon exposure to light of wavelength below 400 nm, the electrical resistivity of the semiconducting nanowires decreases by 4-5 orders of magnitude. ?Nanowire UV photodetector and optical switches?, H. Kind, H. Yan, M. Law, B. Messer, P. Yang, Adv. Mater. 14, 158, 2002 (more...)