An adaptively RF-powered wireless batteryless in vivo EKG and core body temperature sensing microsystem for untethered genetically engineered mice real-time monitoring

An adaptively RF-powered, wireless, batteryless, and implantable electrocardiogram (EKG) and core body temperature sensing microsystem for untethered genetically engineered mice real-time monitoring is designed, implemented, and in vivo characterized. A packaged microsystem exhibits a total size of 9 mm × 7 mm × 3 mm and a weight of 400 mg including a pair of stainless steel EKG electrodes. A low power 2 mm × 2 mm ASIC consisting of an EKG amplifier, a proportional-to-absolute temperature (PTAT) temperature sensor, an RF power sensing circuit, an RF-DC power converter, an 8-bit analog-to-digital converter (ADC), digital control circuitry, and a wireless data transmitter is powered by an adaptively controlled external RF energy source at 4 MHz to ensure a stable on-chip 2 V supply with 156 ¿A DC current for the overall microsystem operation.