Optimization of the Coupling Coefficient of the Inductive Link for Wireless Power Transfer to Biomedical Implants

Table 4

Simulation and measurement results of the inductive link f_p = 25 MHz.

Parameters		Air	Muscle	Bone
Tx resistance (RTx, Ω)	Simulation	1.14	1.94	1.94
	Measurement	1.23	1.87	2.10
Tx inductance (L1, μH)	Simulation	2.60	2.66	2.66
	Measurement	2.57	2.54	2.55
Tx quality factor (Q1)	Simulation	358.12	215.28	214.97
	Measurement	327.76	213.51	190.73
Rx resistance (RRx, Ω)<	Simulation	0.78	0.85	0.94
	Measurement	0.86	0.88	0.91
Rx inductance (L2, μH)	Simulation	0.35	0.36	0.36
	Measurement	0.34	0.33	0.34
Rx quality factor (Q2)	Simulation	70.97	66.48	59.98
	Measurement	61.92	59.75	58.27
Load quality factor (QL)	Simulation	18.06	17.70	17.74
	Measurement	18.78	19.02	18.86
Coupling coefficient (k)	Simulation	0.0212	0.0217	0.0215
	Measurement	0.0213	0.0213	0.0221
Power transfer efficiency (η)	Simulation	55.72%	46.34%	44.40%
	Measurement	52.35%	44.14%	43.07%
Peak value of SAR (W/kg)	Simulation	N.A.	13.58	16.42
The SAR-constrained PDL (mW)	Simulation	N.A.	160.17	123.55
	Measurement	N.A.	145.38	128.13