The design and development of a novel scalp-implantable, nan-invasive, battery free, hybrid wireless sensor system for continuous intracranial pressure (ICP) monitoring are presented. Traditional methods for ICP measurement are highly invasive and pose risks such as infection and trauma. In contrast, the proposed system comprises a radio frequency (RF) powered, hybrid RF biosensor utilising a miniaturised implantable antenna and a wearable non-invasive transceiver. The dual-band operation at 2.45 GHz and 4.55 GHz enables high-data-rate transmission suitable for real-time brain telemetry and for energy harvesting. Electromagnetic simulations utilising human tissue phantoms exhibit robust impedance characteristics, featuring reflection coefficients of − 20.61 dB at 2.45 GHz and − 12.48 dB at 4.55 GHz, alongside fractional bandwidths of 20.42% and 13.85%, respectively. The achieved gains of − 24.08 dBi and − 26.11 dBi are still suitable for biomedical use with very low power. Fabricated prototypes were validated using vector network analyser (VNA) measurements and phantom testing, confirming a strong correlation with simulated performance. The proposed voltage-doubler rectifier, which forms the core of the RF-powered energy supply for the RF-powered telemetry platform for ICP monitoring sensor, was evaluated over an RF input power range of − 20 dBm to 20 dBm. The rectifier shows a monotonic increase in output voltage and power, achieving approximately 1.5 V and 15 mW at 10 dBm, with a peak RF-to-DC conversion efficiency of 56%, demonstrating its suitability for low-power biomedical sensing and telemetry. The system offers potential applications in point-of-care diagnostics, neuro-monitoring, and future space-grade healthcare technologies.
Elias et al. (Tue,) studied this question.