Sensors (Jul 2023)

Passive Impedance-Matched Neural Recording Systems for Improved Signal Sensitivity

  • Sk Yeahia Been Sayeed,
  • Ghaleb Al Duhni,
  • Hooman Vatan Navaz,
  • John L. Volakis,
  • Markondeya Raj Pulugurtha

DOI
https://doi.org/10.3390/s23146441
Journal volume & issue
Vol. 23, no. 14
p. 6441

Abstract

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Wireless passive neural recording systems integrate sensory electrophysiological interfaces with a backscattering-based telemetry system. Despite the circuit simplicity and miniaturization with this topology, the high electrode–tissue impedance creates a major barrier to achieving high signal sensitivity and low telemetry power. In this paper, buffered impedance is utilized to address this limitation. The resulting passive telemetry-based wireless neural recording is implemented with thin flexible packages. Thus, the paper reports neural recording implants and integrator systems with three improved features: (1) passive high impedance matching with a simple buffer circuit, (2) a bypass capacitor to route the high frequency and improve mixer performance, and (3) system packaging with an integrated, flexible, biocompatible patch to capture the neural signal. The patch consists of a U-slot dual-band patch antenna that receives the transmitted power from the interrogator and backscatters the modulated carrier power at a different frequency. When the incoming power was 5–10 dBm, the neurosensor could communicate with the interrogator at a maximum distance of 5 cm. A biosignal as low as 80 µV peak was detected at the receiver.

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