Table 13.

Summary of energy transfer devices: in vivo examples.

Yea	Organism	Location	Material	Frequency or wavelength	Distance between source and receiver	Critical feature size of implant	Power	Power density	Efficiency	Operation regime	Application	Duration	References
APT
2001	Goat	Subcutaneous space	PZT	1 MHz	15 mm	30 mm (diameter), 5 mm (height)	34 mW	–	–	–	Implants	–	[445]
2013	Human	Heart	WiCS-LV system (commercial)	–	≈10 cm	–	Successfully derived cardiac pacing devices	–	–	–	Cardiac pacing	–	[444]
2016	Pig	Subcutaneous space	PZT (commercial)	1 MHz	10–15 mm	70 mm (diameter)	300 mW	–	–	–	Implants	5 weeks	[440]
2016	Rat	Peripheral nervous system and skeletal muscle	PZT	1.85 MHz	8.8 mm	0.8 × 3 × 1 mm3	40 μW	–	–	–	Peripheral nerve neuro recording	–	[442]
WPT
2015	Rat	Near stomach	–	1 MHz	5–10 mm	20 mm (diameter)	127 mW	40.4 mW cm−2	–	Near-field	Peripheral nerve prostheses	–	[470]
2009	Pig	Lower abdomen	–	7 MHz	10 cm	41 mm	Lighting an LED	–	–	Near-field	Brain and subcutaneous implants	–	[465]
2015	Pig	Skull	–	907.5 MHz	27 mm	1 mm3	26.8 mW	26.8 W cm−3	–	Near-field	Brain-machine interface	–	[466]
2014	Pig	Chest and brain	–	1.6 GHz	5 cm	2 mm (diameter), 3.5 mm (height)	2.2, 1.7 mW (brain, heart)	200, 155 mW cm3 (brain, heart)	–	Mid-field	Cardiac pacing	–	[91]
2014	Rabbit	Heart	–	1.6GHz	5 cm	2 mm (diameter), 3.5 mm (height)	Powering a cardiac pacer	–	–	Mid-field	Cardiac pacing	–	[91]
2017	Pig	GI tract	–	1.2 GHz	–	6.8 × 6.8 mm2	37.5, 123, and 173 μW (esophagus, stomach, colon)	81, 266, and 374 μW cm−2 (esophagus, stomach, colon)	–	Mid-field	Ingestible electronics	–	[459]
2011	Rabbit	Eye	–	3 GHz	5 cm	8 × 4 × 2 mm3	300 mW	4.69 W cm−3	–	Far-fie Id	IOP monitoring	–	[106]
Optical power transfer
2012	Rats	Eye (subretinal region)	Silicon	880 nm	–	0.8 mm × 1.2 mm	480 μW	50 mW cm−2	–	NIR	Retinal prosthesis	90 days	[492]
2013	Rats	Eye (subretinal region)	Silicon	915 nm	–	0.8 mm × 1.2 mm	240 μW–2 mW	25–210 mW cm−2	–	NIR	Retinal prosthesis	6 months	[493]
2015	Rats	Eye (subretinal region)	Silicon	880–915 nm	–	1 mm × 1 mm	550 μW	55 mW cm−2	–	NIR	Retinal prosthesis	–	[474]
2016	Rats	Subcutaneous space (back)	GaInP/GaAs	Standard solar spectrum (AM1.5g)	539–675 μm	760 μm × 760 μm × 14	647 μW	10 mW cm−2	6.9–9.5%	Sunlight	Pacemaker	4 weeks	[489]
2017	Rats	Subdermal, bone, muscle, organs, thorax	Silicon	850 nm	15–4 mm	1.23 mm2	0.21–9.53 μW	17–77.5 μW cm−2	0.12–5.79%	NIR (low intensity)	Mm scale depth implants	–	[476]
2017	Rats	Subdermal, bone, muscle, organs, thorax	GaAs	850 nm	15–4 mm	1.23 mm2	0.36–15.1 μW	29–1224 μW cm−2	0.21–9.13%	NIR (low intensity)	Mm scale depth implants	–	[476]
2018	Rats	Infrascapular region	Silicon	780 nm	2 mm	390 μm × 410 μm × 72	64.4 μW	560 μW cm−2	0.28%	NIR (low intensity)	Biodegradable implants	4 months	[491]