A Wireless Adiabatic Stimulator System with Current-Mode Power Reception and Stimulus Current Regulation Achieving Precise Charge Delivery and Electrode Scalability for Miniaturized Electroceuticals

Electroceuticals that directly stimulate nerves are attracting attention as their effectiveness on various intractable diseases has been verified [1]. In such wireless implantable neurostimulators, miniaturizing the receiver (RX) module and downsizing the electrodes are essential (Fig. 35.5.1). However, reducing the RX coil size for miniaturization decreases the received power significantly. Thus, an energy-efficient stimulator that delivers a proper amount of charge with both a high power conversion efficiency (PCE) and a high stimulation efficiency factor (SEF) [4] is required. As the electrode size decreases and thus electrode-tissue-impedance (ETI) becomes high, achieving high PCE when a stimulus current (ISTIM) is low becomes necessary while ensuring insensitivity to high ETI is imperative for accurate charge delivery. Furthermore, to support electrode scalability, the stimulator must withstand high ETI voltage (VT).