A Human–Machine Interface Using Electrical Impedance Tomography for Hand Prosthesis Control

Abstract

This paper presents a human-machine interface that establishes a link between the user and a hand prosthesis. It successfully uses electrical impedance tomography, a conventional bio-impedance imaging technique, using an array of electrodes contained in a wristband on the user's forearm. Using a highperformance analog front-end application specific integrated circuit (ASIC) the user's forearm inner bio-impedance redistribution is accurately assessed. These bio-signatures are strongly related to hand motions and using artificial neural networks, they can be learned so as to recognize the user's intention in real-time for prosthesis operation. In this work, eleven hand motions are designed for prosthesis operation with a gesture switching enabled sub-grouping method. Experiments with five subjects show that the system can achieve 98.5% accuracy with a grouping of three gestures and an accuracy of 94.4% with two sets of five gestures. The ASIC comprises a current driver with common-mode reduction capability and a current feedback instrumentation amplifier (that occupy an area of 0.07 mm 2). The ASIC operates from ±1.65 V power supplies and has a minimum bio-impedance sensitivity of 12.7 mΩp-p.

Control Methods for Transradial Prostheses Based on Remnant Muscle Activity and Its Relationship with Proprioceptive Feedback

“…Due to the non-invasive nature of the method, it has been widely used in clinical applications such as sensing changes in lung ventilation, brain function, and blood flow. For hand gesture recognition, the electrodes are typically wrapped around the forearm near to the wrist; however, any position along forearm is acceptable (as demonstrated by Wu et al [ 58 ] for control of a hand prosthesis) as long as the changes in impedance are large enough to be registered by the system and distinguished as separate gestures. Zhang et al proposed [ 59 ] a wearable wrist-worn EIT device, which adopted a two-terminal measurement scheme with eight electrodes to recognize a set of eight hand gestures in real-time while achieving a high accuracy (96% when worn on the wrist and 93% for proximal forearm placement).…”

Time Stamp – A Novel Time-to-Digital Demodulation Method for Bioimpedance Implant Applications

“…3(a). The current driver is an application specific integrated circuit (ASIC-1) based on [3]. It comprises a master current source (CD+) using an excitation voltage &'( as input, and a slave current sink (CD-) providing the current return path.…”

“…It has a wide range of applications that can help in clinical status monitoring and diagnosis of diseases [2]. Example applications include human-machine interfaces [3], lung function monitoring [4], drug-screening [5], biosensing [6], and cancer detection [7].…”

A 122 fps, 1 MHz Bandwidth Multi-Frequency Wearable EIT Belt Featuring Novel Active Electrode Architecture for Neonatal Thorax Vital Sign Monitoring

“…LECTRICAL impedance tomography (EIT) is an impedance mapping technique that can be used to image the inner impedance distribution of the subject under test. Ever since the feasibility of EIT was first reported in the 1980s by Barber and Brown [1], this technique has been intensively researched towards a non-invasive imaging modality for clinical applications [2]- [5].…”