A probe-antenna and a multifunctional single-pole-four-throw switch are proposed for biomedical neural implants. The multifunctional switch is fabricated in TSMC 90-nm CMOS process and occupies the core area of 297 × 248 μm2. Operating in transmitter/receiver mode, the switch achieves the insertion loss of 4.5/4.8 dB, return loss of 16.7/15.4 dB, isolation of 19.2/20.3 dB and P1dB of 4/5 dBm at 60 GHz. Based on the dipole antenna, the antenna with probe function is designed and fabricated on the Roger 4003C two-layer printed circuit board. This probe-antenna achieves the input matching over 59.35-65 GHz. According to the simulation, it achieves the radiation efficiency of 69.8/34.4% and gain of 3.88/5.47 dBi without/with a drop of deionized water on the feed. The probe/electrode function is verified by performing impedance measurement on the deionized water, phosphate buffered saline (PBS) solution, and solution with conductivity of 1413 μS/cm.
Keywords: Antenna; Biomedical implants; Electrochemical impedance spectroscopy; Impedance measurement; Neural recording; Probe; Switch.