Table 1 Overview of alternative sources of energy to replace batteries
From: RF power harvesting: a review on designing methodologies and applications
| Source | Power density | Harvesting tech. | Advantages | Disadvantages |
|---|---|---|---|---|
| Solar |
Indoor: 10 µW/cm2
Outdoor: 10 mW/cm2 | Photovoltaic |
High power density Mature |
Not always available Required exposure to light (not implantable) Expensive |
| Vibration |
Human: 4 µW/cm2
Industrial: 100 µW/cm2 |
Piezoelectric Electrostatic Electromagnetic |
Implantable High efficiency |
Not always available Material physical limitation |
| Thermal |
Human: 30 µW/cm2
Industrial: 1–10 mW/cm2 |
Thermoelectric Pyroelectric |
High power density Implantable |
Not always available Excess heat |
| RF |
GSM: 0.1 µW/cm2
WI-FI: 1 mW/cm2 | Antenna |
Always available Implantable |
Low density Efficiency inversely proportional to distance |