Wireless Power Transfer, Recovery, and Data Telemetry for Biomedical Applications

With the advancement of biomedical instrumentation technologies, sensor based remote healthcare monitoring system is gaining more attention day by day. These sensors can be classified as wearable and implantable. Implantable sensors include associated circuits for signal processing and data transmission and are placed inside the human body to acquire the information on the vital physiological phenomena. Powering the circuit is always a crucial design issue. Batteries cannot be used in implantable sensors which can come in contact with blood resulting in serious health risks. An alternate approach is to supply power wirelessly for tether-less and battery-less operation of the circuits. Inductive power transfer is the most common method of wireless power transfer to the implantable sensors. For good inductive coupling, the inductors should have high inductance and high quality factor. But the physical dimensions of the implanted inductors cannot be large due to a number of biomedical constraints. Therefore, there is a need for small sized and high quality factor inductors with high values of inductance for implantable sensor applications. On-chip inductors present a potential solution for further miniaturization of the implantable system. Implantable micro-systems require wireless transmission of the sensor data for real-time monitoring and diagnosis. Data telemetry can be achieved using two different schemes: forward telemetry which involves data transmission from power transmitter to power receiver and backward telemetry involving data transmission from power receiver to power transmitter. This chapter also briefly summarizes design of power recovery unit for wireless power recovery and energy conversion in biomedical implants. The basic design blocks of the wireless power recovery unit include matching network, rectifier and DC-DC converter. The charge pump A.B. Islam (*) • D. Costinett • S.K. Islam Department of Electrical Engineering and Computer Science, The University of Tennessee, Knoxville, TN, USA e-mail: ashraf.b.islam@gmail.com; daniel.costinett@utk.edu; sislam@utk.edu # Springer Science+Business Media LLC 2017 M. Sawan (ed.), Handbook of Biochips, https://doi.org/10.1007/978-1-4614-6623-9_15-1 1 based rectifier scheme can be successfully implemented to compensate for the low peak-to-peak voltage caused by coil misalignments and lower coupling in a practical system.