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Flexible functional electrical stimulation architecture with external remote controller for unilateral facial paralysis patients
M. Ganesh Lakshmana Kumar, G.D.V. Santhosh Kumar, R. Sesha Sairam,
Published in Institute of Electrical and Electronics Engineers Inc.
2018
Pages: 3330 - 3335
Abstract
The main disorder of unilateral facial paralysis patients is loss of blink in paralyzed side eye. Functional electrical stimulation (FES) is considered to be one of the promising techniques for recovery of blink. The levels of electrical stimulus required for blink differs from patient to patient based on Electrode-Tissue Impedance (ETI). Hence, the motivation of the present work is to design a programmable stimulator which can accommodate wide range of current stimulus levels suitable for wide variety of patients. The present work targets 8 levels of chopped bi-phasic current stimulation levels ranging from 0.33 mA to 1.51 mA. This architecture is designed with two modes of operation, normal and programmable modes. In normal mode, a trigger signal is required from blink detection circuit from the healthy side. However, in programmable mode, the programmability of different stimulus levels was achieved by an external device with 6 bits of data. In this receiver front-end, Envelope Detector(ED) is stacked on Low Noise Amplifier (LNA) for reusing current with low power. A 3 bit latch is designed to hold current level bits which can program through 6 bit shift register. Switch control logic is designed using a Linear Feedback Shift Register (LFSR) and an AND gate. The proposed architecture in this work is designed with UMC 180 nm CMOS technology. Current reuse LNA and ED features gain of 12.13 dB@2.4 GHz with a noise figure(NF) of 6.77 dB@2.4 GHz and S11 of -18 db@2.4 GHz. Current Stimulator circuit can provide a chopped bi-phasic current pulse which ranges from 336 μA up to 1.5mA for a wide range of Electrode Orbicularis Oculi muscle impedance, Rs=0.1kΩ to 2kΩ, Cp=1nF to 5nF. Current consumption during non-blink, re-programmable and blink trigger are 22.5μA,37.5μA and 362μA to 1.51mA respectively. © 2018 IEEE.