Contents I. Introduction
The future of wearable artificial skin sensors requires inexpensive, flexible, easy to read sensors with highly sensitive, noise-robust measurements. Traditionally, touch sensor plat-forms are rigid, or consist of an array of many local sensors, one for each sensitized location. Conductive elastomer materi-als whose internal conductivity changes with external strain are a promising solution for inexpensive, easy-to-fabricate touch sensors for artificial skin applications [1]–[3]. However, in contrast to the readout simplicity of traditional touch arrays, the use of conductive elastomers requires a higher degree of readout complexity. Electrical impedance tomography (EIT) is a non-invasive imaging modality whereby resistance measurements taken from the material periphery are used to reconstruct the internal conductivity. In the context of elastomer sensors, when the elastomer's conductivity changes under local strain, such a readout method for material sensing can turn the entire elastomer area into a sensor, with peripheral contacts that make best use of the sensing surface area. When EIT is applied using the sensitivity volume (SV) method previously proposed by the authors [4], resolution and noise limitations of standard EIT methods [5]–[13] can be overcome. Examples of the challenges of traditional EIT include low resolution in the central regions of sensors [14]–[16] and difficulty in identifying two simultaneous press events [11], [12]. In this work, we will demonstrate an artificial skin sensor that uses the SV method for 2D electrical impedance tomography for real time, noise robust sensing and the ability to distinguish between multiple press events.
