A low-power IC design for the wireless monitoring system of the orthopedic implants

This paper proposes an architecture of the wireless monitoring system for the real-time monitoring of the orthopedic implants. The system monitors the implant duty cycle, detects abnormal high amounts of force, and other conditions of the orthopedic implants. Data for diagnosis is communicated wirelessly by radio frequency (RF) signal between the embedded chip (inside body) and the remote circuit (outside body). In different working modes the system can be powered by the RF signal or stiff lead zirconate titanate (PZT) ceramics which are able to convert mechanical energy inside the orthopedic implant into electrical energy. The radio frequency (RF) circuits with the working frequency of 2.4 GHz have been taped out with 0.18 mum CMOS technology with 50 muW. It can supply 400 muW power over a distance of 20 cm between the two transceivers. The power circuits have been taped out with 0.35 mum CMOS technology. The circuits including RF circuits, analog digital converter (ADC), and micro control unit (MCU) have been implemented in 0.18 mum CMOS process.