Temperature and Strain Compensation for Flexible Sensors Based on Thermosensation

Abstract

Flexible sensors have wide applications in wearable electronics, health monitoring, humanoid robotics, and smart prosthesis. Problems of temperature drift and bending/stretching strain are challenging and should not be neglected in practical applications of flexible sensors. Here, we report a novel temperature and strain compensation method for thermosensation-based flexible sensors. Thermosensation is human-skin-inspired perception, which inspires diverse flexible sensors (pressure sensor, flow sensor, temperature sensor, material sensor, proximity sensor, etc.) and multisensory electronic skin. Thermosensation-based flexible sensors utilize thin-film sensing thermistors to detect external physical stimuli through perceptions of the conductive and convective heat transfers toward the surroundings, which enables high-density integration of multisensations while minimizing complexity due to the uniform sensing principle of thermistors that have simple structures and easy operations. To overcome the negative effects of temperature drift and bending/stretching strain in these flexible sensors, we propose to monolithically integrate a compensating thermistor that has a similar geometric shape and is of the same material with the sensing thermistor into a Wheatstone-bridge feedback circuit. When the sensing and compensating thermistors meet geometric similarity, the compensations of temperature and strain are self-sustained by a feedback control of a circuit. The effectiveness is validated through theoretical analysis and experiment measurements. As examples, flexible pressure sensor and flexible flow sensor with temperature and strain compensations are demonstrated. Results indicate that the temperature and strain effects can be tremendously eliminated using the proposed compensation method, which is fast, self-sustained, and expedient to realize. The compensation method enriches competences of flexible sensors and demonstrates competitive advantages for diverse flexible and stretching applications of wearable electronics.

Printable, Highly Sensitive Flexible Temperature Sensors for Human Body Temperature Monitoring: A Review

“…The fabricate of flexible sensors requires the sensor itself to be flexible, stretchable, and ductile and the substrates and circuits on which it depends. Specific stretch and stretch characteristics to adapt to the adhesion on the human body surface, common flexible substrates are usually processed into a film, such as polydimethylsiloxane (PDMS) [ 17 – 20 ], polyimide (PI) [ 21 , 22 ], polyurethane (PU) [ 23 ], polyethylene terephthalate (PET) [ 24 , 25 ], polyvinyl alcohol(PVA) [ 26 ], polyvinyl butyral(PVB) [ 27 ], paper [ 28 , 29 ], silicone rubber [ 5 , 30 , 31 ], and more skin-friendly biodegradable materials can also be used, such as pectin [ 32 ], cotton, silk [ 33 ], and other cellulose materials [ 34 , 35 ].…”

A Fully Flexible Intelligent Thermal Touch Panel Based on Intrinsically Plastic Ag2S Semiconductor

“…Due to the Ag 2 S film is not sensitive to stress (see Figure S5a, Supporting Information) and the force of the finger touch is actually very small, which may only cause little elastic deformation to the Ag 2 S film. [21,39] Such slight deformation contributes very weakly to the physical properties, including thermal conductivity, electrical conductivity and so on. Arbitrary types of finger touch can be used to operate the touch panel independent of the touch stress.…”

A wearable motion capture device able to detect dynamic motion of human limbs

“…The micro flow sensor (shown in Supplementary Fig. 9 ) is made by the following steps 62 : (i) Spin coating a 30 μm photoresist (KXN5735-LO, Rdmicro Co. Ltd.) on a polyimide substrate (AP8525R, DuPont Co. Ltd.). (ii) Obtaining the pattern by photolithography and development.…”