Harnessing metamaterials for efficient wireless power transfer for implantable medical devices

Table 1 Comparative overview of recent metamaterials demonstrated to enhance powering of IMDs

	Metamaterials situated between transmitter and receiver coil				Metamaterial acting as transmitter coil
Reference	(Shaw and Mitra 2019)	(Li et al. 2018)	(Wang et al. 2021)	(Chen et al. 2019)	(Agrawal et al. 2017)	(Alshhawy et al. 2022)	(Pokharel et al. 2021)
Metamaterial Properties
Total Size (mm²)	30 × 30	21 × 21	60 × 60	500 × 500	60 × 60	20 × 20	60 × 60
Operating Frequency (MHz)	430	272–1504	1600	13.56	1600	50	50
Transmitter Size (mm²)	90 × 90	40 × 40	N/A	N/A	N/A	N/A	N/A
Receiver Size (mm²)	12 × 12	10 × 12	12 × 12	10 × 10	1.5 × 3	7 × 7	10 × 10
Tx to Metamaterial Distance (mm)	53	70	50	5	N/A	N/A	N/A
Rx to Metamaterial Distance (mm)	18	13	6	5	42	9	10
PTE without metamaterial (%)	0.34	0.002	0.01	N/A	N/A	N/A	N/A
PTE Improvement with Metamaterial (%)	1.11	1.6	1.45	5	N/A	2.5	6
FOM	4.89	2.68	0.18	0.63	4.37	5.31	6.00
Max Excitation Power in Tx coil (mW)	180	N/A	N/A	N/A	800	130	168

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