Friday, February 17, 2017
Exhibit Hall (Hynes Convention Center)
Andrei Spiride, Texas Junior Academy of Science, Plano, TX
8-10% of the US population use implantable medical devices (IMDs) to improve quality of life, or increase lifespan. Batteries powering IMDs dominate device size and cost and require replacement. Surgery risks and smaller sized medical devices make batteries less attractive as primary power sources and alternative techniques of energizing IMDs are needed.

This project characterized the performance of a noninvasive wireless energy transfer method for IMDs. A prototype biocompatible power generator uses a piezo ceramic bimorph excited by low frequency oscillations produced by a massager. When excited by the massager vibration, the piezo produced voltage is rectified to yield 3.7V DC regulated output across a load.

A total of 31 experiments were conducted, each collecting an average of 31,000 data points during 6 minutes each. Experiments tested four hypotheses varying the piezo tip tuning mass, massager speed settings, series vs parallel bimorph side connection, and PZT ceramic vs. PVDF foil piezos. All experiments used the same massager, voltage regulator and Arduino circuit, and sealed enclosure design materials.

Tests confirmed the effectiveness of using a 1g tuning mass to better match the piezo natural resonance frequency to the massager oscillation frequency. Data showed piezo power generation performance sensitivity to massager speed settings with higher speeds resulting in increased efficiency.

The experiments demonstrate that the piezo power prototype generates power amounts compatible with the power consumption needs of practical applications such as implantable cardiac defibrillator and pacemaker devices. A detailed error analysis was included and several directions for future work identified.