UCLA researchers in the Department of Electrical and Computer Engineering have developed a battery-less implantable pulse generator with concise circuitry and mm-scale form factor.
Implantable pulse generators (IPGs) are used clinically for chronic pain relief, motor function recovery after spinal cord injury, treatment of gastroesophageal reflux disease, cardiac pace-making, and curing stress urinary incontinence. Conventional IPGs are bulky, with the battery taking up most of the unit, and contain obligatory leads, which are prone to cause various complications including: dislodgement, infection, and embolism. These limitations have led to a demand for battery-less and leadless IPGs that can be directly implanted in a specific anatomical region. Proposed energy-efficient IPGs include the use of ultrasound-based IPGs, which have smaller form factors but require the use of ultrasound gel and have issues with pulse propagation through air-filled viscera (such as the lung and bowel) and other anatomical obstructions (such as bones). Passive circuits have also been investigated to realize energy-efficient IPGs, but they require sudden bursts of strong signal set periods of time (Tx power), which are prone to violate specific absorption rate (SAR) testing and regulations.
UCLA researchers have developed a battery-less IPG with a mm-scale form factor and concise circuitry. To achieve a high reception sensitivity, the proposed IPG consumes one of the lowest static powers among active circuitry-based works.A novel notch-modulation scheme precisely controls the rate and intensity of the output pulses. The device has been successfully prototyped with a form factor of 4.6 mm × 7 mm. As the circuitry only consumes about 3μW static power, this work complies with SAR regulations. In addition, with a Tx power of 1 W, benchtop measurements of the device demonstrate a maximum operating distance of 4.5 cm and 4 cm in the air and through fresh water, respectively. The quiescent power consumption of this device is one of the lowest among active circuitry-based IPGs, showcasing the potential for applications requiring extremely small form factors and high sensitivities.
Device was successfully prototyped, benchtop verified, and tested in vivo in a small animal model for neuromuscular stimulations. The IPG was implanted in a hind limb muscle belly rat model and ankle flexion forces with controllable strengths and rates.
Leadless pacemaker, wireless device, medical device, small form factor, low power consumption, implantable pulse generators (IPGs)