Table 2.

Specification summary of the implanted stimulator.

Hermtically packaged stimulator	35 mm(L) $\times$ 26 mm (W) $\times$ 8 mm (H)
Diameter of internal coil	28 mm
Length of lead between electrode and stimulator	20 cm
Stimulator electrode	4 mm $\times$ 4 mm
Stimulation site of the electrode	750 um $\times$ 300 um
Electrode site impedance	1300 ± 106 ohm at PBS solution pH 7.4
Number of current generator	7
Data packet	22 bits
Stimulation duration (number of bits; minimum duration)	4-bit (200 us)
Stimulation amplitude (number of bits; minimum amplitude)	8-bit (8 uA)
Power consumption (520 uA, 1 ms, 4 Hz)	2 mw
Rechargeable battery size	20 mm (D) $\times$ 4 mm (H)
Rechargeable battery capacity	75 mAh (4.2 V)
Recharging time	3 hours (25 mA charging current)