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Development of a High-Speed Current Injection and Voltage Measurement System for Electrical Impedance Tomography-Based Stretchable Sensors

Autonomous System and Robotics Research Centre, University of Salford, Manchester M5 4WT, UK
Research Centre E. Piaggio, University of Pisa, 56122 Pisa, Italy
Department of Information Engineering, University of Pisa, 56122 Pisa, Italy
Author to whom correspondence should be addressed.
Technologies 2017, 5(3), 48;
Received: 12 July 2017 / Revised: 20 July 2017 / Accepted: 21 July 2017 / Published: 26 July 2017
(This article belongs to the Special Issue Wearable Technologies)
PDF [8301 KB, uploaded 26 July 2017]


Electrical impedance tomography (EIT) is an imaging method that can be applied over stretchable conductive-fabric materials to realize soft and wearable pressure sensors through current injections and voltage measurements at electrodes placed at the boundary of a conductive medium. In common EIT systems, the voltage data are serially measured by means of multiplexers, and are hence collected at slightly different times, which affects the real-time performance of the system. They also tend to have complicated hardware, which increases power consumption. In this paper, we present our design of a 16-electrode high-speed EIT system that simultaneously implements constant current injection and differential potential measurements. This leads to a faster, simpler-to-implement and less-noisy technique, when compared with traditional EIT approaches. Our system consists of a Howland current pump with two multiplexers for a constant DC current supply, and a data acquisition card. It guarantees a data collection rate of 78 frames/s. The results from our conductive stretchable fabric sensor show that the system successfully performs voltage data collection with a mean signal-to-noise ratio (SNR) of 55 dB, and a mean absolute deviation (MAD) of 0.5 mV. The power consumption can be brought down to 3 mW; therefore, it is suitable for battery-powered applications. Finally, pressure contacts over the sensor are properly reconstructed, thereby validating the efficiency of our EIT system for soft and stretchable sensor applications. View Full-Text
Keywords: EIT; stretchable; pressure sensor; conductive fabric; wearable EIT; stretchable; pressure sensor; conductive fabric; wearable

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Russo, S.; Nefti-Meziani, S.; Carbonaro, N.; Tognetti, A. Development of a High-Speed Current Injection and Voltage Measurement System for Electrical Impedance Tomography-Based Stretchable Sensors. Technologies 2017, 5, 48.

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