An implantable electrical stimulator for phrenic nerve stimulation

Abstract

Phrenic nerve stimulation is a technique whereby a nerve stimulator provides electrical stimulation of the phrenic nerve to cause diaphragmatic contraction in patients with respiratory failure due to cervical spinal cord injury. This paper presents an eigth-channel stimulator circuit with an output stage (electrode driving circuit) that doesn’t need off-chip blocking-capacitors and is used for phrenic nerve stimulation. This stimulator circuit utilizes only 1 output stage for 8 channels. The proposed current generator circuit in this stimulator reducing to a single step the translation of the digital input bits into the stimulus current, thus minimizing silicon area and power consumption. An 8 bit implementation is utilized for this current generator circuit. The average pulse width for this eight- channel stimulator with 1 mA current, 20 Hz frequency and 8 bits resolution, is 150 - 300 μs. The average power consumption for a single-channel stimulation is 38 mW from a 1.2 V power supply. This implantable stimulator system was simulated in HSPICE using 90 nm CMOS technology.