MEMS-Based Power Generation Techniques for Implantable Biosensing Applications

Abstract

Implantable biosensing is attractive for both medical monitoring and diagnostic applications. It is possible to monitor phenomena such as physical loads on joints or implants, vital signs, or osseointegration in vivo and in real time. Microelectromechanical (MEMS)-based generation techniques can allow for the autonomous operation of implantable biosensors by generating electrical power to replace or supplement existing battery-based power systems. By supplementing existing battery-based power systems for implantable biosensors, the operational lifetime of the sensor is increased. In addition, the potential for a greater amount of available power allows additional components to be added to the biosensing module, such as computational and wireless and components, improving functionality and performance of the biosensor. Photovoltaic, thermovoltaic, micro fuel cell, electrostatic, electromagnetic, and piezoelectric based generation schemes are evaluated in this paper for applicability for implantable biosensing. MEMS-based generation techniques that harvest ambient energy, such as vibration, are much better suited for implantable biosensing applications than fuel-based approaches, producing up to milliwatts of electrical power. High power density MEMS-based approaches, such as piezoelectric and electromagnetic schemes, allow for supplemental and replacement power schemes for biosensing applications to improve device capabilities and performance. In addition, this may allow for the biosensor to be further miniaturized, reducing the need for relatively large batteries with respect to device size. This would cause the implanted biosensor to be less invasive, increasing the quality of care received by the patient.

MRI-based communication for untethered intelligent medical microrobots

“…This approach is mainly interested in MEMS device where the mechanical actuation is the final desired energy form. For generating electricity, this approach can be used to actuate electrostatic, electromagnetic, and piezoelectric based generation scheme [52].…”

“…Micro fuel cells generate electricity from controlled electrochemical reactions [52]. They categorized into two classes of regenerative and non-regenerative generation techniques.…”

“…To support power generation, the capacitors must have constant charge during the time; hence, a polarization source must be available to generate additional power [52].…”

“…Three materials that can be used for this application are lead zirconate titanate (PZT), zinc oxide (ZnO) and aluminum nitride (AlN). ZnO and AlN are more commonly used in actuation while PZT is mainly used for power generation purposes [52]. An example of this would be the PZT microfiber generator developed by Ishisaka et al [66] that used the contractions of a heart muscle to actuate the piezoelectric microfiber generator.…”

High Energy Density Capacitance Microgenerators

“…Electrostatic energy microgenerators seem to be the most suitable for this task, because fuel or chemical elements need to be refined or renewed, solar or thermo-elements are not suitable for all situations of MEMS operation, electromagnetic generators of energy are ineffective in the range of low-amplitude vibrations and small sizes of the transducers, while piezoelectric generators are ineffective at low frequencies of vibrations [12][13][14].…”