Design of NFC WISP system for wearable devices

Wearable devices are developing rapidly recent years in multiple areas such as continuous monitoring of human vital signs including body temperature, blood pressure, electrocardiogram, and blood glucose. The increased integration level for wearable devices has proposed higher request for power sources. Conventional button cell has become bulky for epidermal and implantable medical sensing. Wireless power delivery employing RFID technology including near field communication (NFC) is a common solution in such a case. In this paper some related problems for NFC technology such as coil inductor coupling and inductor geometry optimization is discussed and simulated with HFSS. A circuit board of wireless identification and sensing platform (WISP) is designed; experiences for functional test are given out. A wearable sensor system including a NFC interface chip AS3953, a low power MSP430 MCU, a spiral inductor, and a thermometer sensor for human body temperature measurement is proposed with flexible integration by Fan-out WLP procedures.