Figure 4.

Parametric study and optimization of an inductive coupling method. A) Schematic overview of the batteryless wireless system with an implantable flow sensor and two external antenna coils. B) Equipment overview and example excitation signals. Received transient sensor signals differ for on and off resonance cases. C) Experimental validation of optimal number of sensor coil turns to increase amplitude at resonance. D) Signal amplitude according to the frequency showing the largest resonance with a 9‐turn excitation coil and 5‐turn receiving coil (blue curve). E) Minimized noise due to tuning of antenna coils at the frequency range of interest. F) Signal amplitude showing that sensors with thicker Ag (multiple passes) transmitting a larger resonant peak. G) Comparison of excitation magnetic field strength 1 cm away from excitation coil and averaged over a projected area of 20 × 20 cm² with safety limit of 1.6 A m⁻¹. H) CardioMEMS HF system operates with an ERP greater than that used in this work with 5 V. I) In vitro test of the sensor coil and ceramic capacitor in different conditions, including frequency sweeps of sensor coil through air, readable up to 8 cm, J) sensor coil readable up to 7 cm when placed in saline solution, and K) sensor coil with the detection range to 6 cm in meat.