Ultra-Low-Power RF Energy Harvesting and Backscatter Communication System for Implantable Biomedical Sensors

Abstract

The biomedical sensors implantable need stable performance over a long period with very stringent energy levels when battery replacement is not practicable and harvested RF power values normally are very low especially because of tissue attenuation. The following paper describes ultra-low-power RF energy harvesting and backscatter communication system which is optimised to be used in implantable applications. The suggested architecture incorporates a downsized implant antenna, a multi-stage low-threshold rectifier, and a low-weight maximum power point tracker maximized controller considering sub- mW to several- mW operating conditions. A low-overhead incentive-conduction approach in which operation is duty-cycled is used by MPPT algorithm to reduce controller consumption while ensuring the algorithm converges at a rapid rate with changing RF input conditions. Results in the context of experiment and simulation indicate a highest RF to DC conversion efficiency of up to 60 percent and maintained efficiency over 50 percent at a low input power of down to -18 dBm. The system has a cold-start sensitivity of -19 dBm, which increases the range of operation in biological tissue. The proposed adaptive tracking design is 25 percent better harvested power than a fixed-load solution (with controller overhead of less than 2). Backscatter communication with an integrated backscatter allows transmission of data at 50 -100 bps with a bit error rate of less than 10 -3 over short biomedical telemetry links of short range. The analysis of specific absorption rate (SAR) verifies the adherence to the biomedical standards of safety. These findings confirm the proposed MPPT-enabled harvesting architecture has a tremendous benefit of improving stability of energy, sensitivity and reliability of communication abilities thus making it a viable system in long-term battery-less implantable applications requiring sensing.