Abstract
This paper presents the fabrication and implementation of novel resistive sensors that were implemented for strain-sensing applications. Some of the critical factors for the development of resistive sensors are addressed in this paper, such as the cost of fabrication, the steps of the fabrication process which make it time-consuming to complete each prototype, and the inability to achieve optimised electrical and mechanical characteristics. The sensors were fabricated via magnetron sputtering of thin-film chromium and gold layer on the thin-film substrates at defined thicknesses. Sticky copper tapes were attached on the two sides of the sensor patches to form the electrodes. The operating principle of the fabricated sensors was based on the change in their responses with respect to the corresponding changes in their relative resistance as a function of the applied strain. The strain-induced characteristics of the patches were studied with different kinds of experiments, such as consecutive bending and pressure application. The sensors with 400 nm thickness of gold layer obtained a sensitivity of 0.0086 Ω/ppm for the pressure ranging between 0 and 400 kPa. The gauge factor of these sensors was between 4.9–6.6 for temperatures ranging between 25 °C and 55 °C. They were also used for tactile sensing to determine their potential as thin-film sensors for industrial applications, like in robotic and pressure-mapping applications. The results were promising in regards to the sensors’ controllable film thickness, easy operation, purity of the films and mechanically sound nature. These sensors can provide a podium to enhance the usage of resistive sensors on a higher scale to develop thin-film sensors for industrial applications.
Highlights
The use of sensors for ubiquitous sensing has been a cornerstone for the electronics industry for the last two decades [1,2]
The current paper focuses on the use of commercial polyimide films, sputtering with a thin-film layer of gold to form the conductive sensing surface of the sensors
Since the sensing area of the prototypes consists of a gold and chromium sputtered thin-film layer, this increase is dictated by their conducting paths
Summary
The use of sensors for ubiquitous sensing has been a cornerstone for the electronics industry for the last two decades [1,2]. For electrodes, even though different kinds of carbon-based allotropes, such as carbon nanotubes [15,16] and graphene [17,18], have been used to form flexible sensors, certain disadvantages—including the high cost of fabrication and short lifetime creates a requirement for alternative conductive materials to be considered for strain-induced applications To address this requirement, the current paper focuses on the use of commercial polyimide films, sputtering with a thin-film layer of gold to form the conductive sensing surface of the sensors. The multi-functionality of these sensors can be highlighted by using them as wearable prototypes that are capable of sustaining prolonged wear and tear due to the robustness of polyimide and thin-film gold layer Another advantage of the proposed sensors is related to their working principle, as they are cheap and easy to fabricate, possess a higher range of resistance values, and have higher efficiencies and faster responses compared to the capacitive counterparts. The conclusion is given in the final section of the paper
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