Low-grade-heat energy harvesting using superlattice thermoelectrics for applications in implantable medical devices and sensors

All implantable medical devices (IMDs), including pacemakers, defibrillators, drug infusion pumps, and pain management technology require electrical power. One limitation of implantable biomedical devices is the longevity of the battery source. Currently, the longevity of pacemakers and defibrillators ranges from 5 to 10 years depending on the model and pacing requirements. After 5-10 years, the patient has to undergo surgery for the pacemaker to be removed and the battery replaced. A solution to this problem would be to use temperature differences, typically as low as 0.3 to 1.5°C that can exist between the inner surface of the skin and the core body temperature to create electrical energy. A thermoelectric module generating 70 μW or more from such temperature gradients can be useful in such applications. The module can be useful to supplement the battery power. Beyond the medical devices market, these thermal batteries could also be used to power wireless sensors. In order to truly achieve "wireless" and untethered/unattended operation, it would be desirable to have self sustaining power or energy harvesting.