A Non-Linear Model of an All-Elastomer, in-Plane, Capacitive, Tactile Sensor Under the Application of Normal Forces

Abstract

In this work, a large deformation, non-linear semi-analytical model for an all-elastomer, capacitive tactile unit-sensor is developed. The model is capable of predicting the response of such sensors over their entire sensing range under the application of normal forces. In doing so the finite flat punch indentation model developed earlier is integrated with a capacitance model to predict the change-in-capacitance as a function of applied normal forces. The empirical change-in-capacitance expression, based on the parallel plate capacitance model, is developed to account for the fringe field and saturation effects. The elastomeric layer used as a substrate in these sensors is modeled as an incompressible, non-linear, hyperelastic material. More specifically, the two term Mooney-Rivlin strain energy function is used as a constitutive response to relate the stresses and strains. The developed model assumes both geometrical as well as material non-linearity. Based on the related experimental work presented elsewhere, the inverse analysis, combining finite element (FE) modeling and non-linear optimization, is used to obtain the Mooney-Rivlin material parameters. Finally, to validate the model developed herein the model predictions are compared to the experimental results obtained elsewhere for four different tactile sensors. Great agreements are found to exist between the two which shows the model capabilities in capturing the response of these sensors. The model and methodologies developed in this work, may also help advancing bio-material studies in the determination of biological tissue properties.

Negative Capacitance and Intrinsic Ferroelectric Behavior in α-MoO3 Culminating as a Robust Piezoelectric Energy Harvester

“…When the electrode thickness or width approaches the electrode gap, saturation under increasing compressive loads via the transient zone seems to form, as shown in Figure a. This is particularly due to the emergence of fringe field effects in the system . The dielectric sensitivity in the linear region was found to be 56 pF/N in terms of capacitance per unit force .…”

“…This is particularly due to the emergence of fringe field effects in the system. 41 The dielectric sensitivity in the linear region was found to be 56 pF/N in terms of capacitance per unit force. 42 In principle, every dielectric ceramic may be thought of as the phasor combination of equivalent series resistance (ESR) and capacitive reactance in an impedance plane.…”

Motion Detection Using Tactile Sensors Based on Pressure-Sensitive Transistor Arrays

“…The sensor devices have different characteristics that are important for target applications, and can be fabricated using various principles. The forms include piezoelectric [26,27], capacitive [28][29][30], piezoresistive [31,32] and field-effect transistor types, depending on the parameters to be achieved [33][34][35][36]. Here, we present basic information about the tactile sensor array device, which is used extensively as a tool for recognizing gestures, so that readers can gain a better understanding of the fundamental mechanisms involved.…”

Nonlinear Poisson's Ratio for Modeling Hyperelastic Capacitive Sensors

“…[ 24 ] In addition, fillers in the silicone matrix can result in a strain‐dependent Poisson's ratio. [ 19,21,25,26 ] Nonlinear capacitance models for pressure sensors highlight the importance of accurate material assumptions, [ 27,28 ] but, to the authors’ knowledge, no study provides empirical evidence for a nonlinear capacitance model for stretch sensors, and there are no studies investigating the potential strain‐dependent Poisson's ratio of capacitive sensors.…”