Development of two-dimensional interdigitated center of pressure sensor

Abstract

This paper presents the development of a two-dimensional (2D) flexible patch sensor to detect and monitor the center of pressure (CoP) location and the total magnitude of a spatially distributed pressure to the specific surface areas of engineering structures. The CoP sensor with the contact mode induced by a pressure distribution was formulated by force sensitive resistor technology and was mainly composed of a thin conductive polymer layer, adhesive spacers, and two interdigitated patterned electrode films with unique sensing aperture shadings. By properly mapping the interdigitated electrode patterns to the top and bottom surfaces of the conductive polymer, the proposed sensor ideally enables to measure an overall applied pressure level and its centroid location within a predetermined sensing region in real-time. The CoP sensor containing 36 sensing sections within a dimension of around 3 × 3 inches was prototyped and experimentally investigated to verify its capability to identify the CoP location and magnitude due to the presence of a permanent magnet-based local pressure distribution. Only five electric wires connected to the CoP sensor to inspect the pressure-sensing positions of 36 segments. The evaluation results of the measured sensor data demonstrate good agreements with the actual test parameters such as the total pressure and its centroid position with about 5% locational error. However, to provide accurate information on the overall pressure range, the compensation factors must be determined and applied to the individual sensing sections of the sensor.

Characteristic Evaluation of Pressure Mapping System for Patient Position Monitoring in Radiation Therapy

“…These definitions of the COP lat (t) and COP lng (t) provide the total pressure at time t and the ratio relative to the pressure center location along with a continuously distributed sensor [19].…”

Optimizing Pressure Matrices

“…If one moves a finger from one strip to the next at a fixed speed, the transition occurs faster if the motion is perpendicular to the strips than if the strips are arranged diagonally. Yoo and Pines demonstrate this approach in a 'center of pressure' sensor [34], however they chose a design which only supports input at discrete positions. Triangular interdigitated designs can also be found in white-papers and application notes for capacitive slider design [15,30] and are also common in the DIY community: They are being explored in Paris based textile hackerspace Datapaulette, they can be found in the web-archive by Satomi and Perner-Wilson [38], as Instructables by Freire [37] or in the eTextile swatchbook [11] (see also Figure 1).…”

“…Our goal is to maximize the sensing resolution of pressure sensor matrices by methods other than increasing the electrode count. This can be done by leveraging the conductive properties of the resistive material [27], by interpolating the collected data [6], or by using diagonal or triangular electrode designs which create gradual transitions from one electrode to the next [34]. The latter approach, which we refer to as interdigitation, is quite common in DIY context (Figure 1, b,c,d,e), and can be found in product briefs and white-papers [15,30].…”

A Flexible and Ultra-Highly Sensitive Tactile Sensor through a Parallel Circuit by a Magnetic Aligned Conductive Composite

“…Meanwhile, the carbon-based conductive fillers, with a sufficient mechanical property as well as light weight, are broadly applied in piezoresistive sensors, possessing a tremendous potential in pressure-response displays, animal movement detecting, healthcare monitoring, etc . , Therefore, microscale carbon-based fillers, e.g ., graphene, carbon black, or carbon fibers, become a preferred choice for future high-performance and mass-manufactured soft tactile sensors . Recently, these piezoresistive sensors based on microscale carbon-based fillers have mainly been demonstrated by two strategies as follows: first, the porous conductive active layer (hollow spherical structure or sponges); second, bionic microstructures (fish-scale-like sensing layer, cracks, interlocking, and pyramid). − Although these structures contribute to sensing sensitivity, the sensitivity is limited by little change of resistance. − In more detail, the resistance of the device changes dominantly relies on its structural compression ratio and the interconnection of conductive pathways. And the magnitude of these resistance changes, in turn, reflects the sensitivity, which is of paramount importance for the pressure sensor.…”