V₂O₅ Thin Films for Flexible and High Sensitivity Transparent Temperature Sensor

Abstract

This work reports the optimization of V 2 O 5 Seebeck coeffi cient to obtain high sensitivity and transparent temperature sensors. It is observed that the fi lm thickness plays a major role on the thermoelectric properties, together with the annealing step, obtaining a Seebeck coeffi cient of −690 µV K −1 , for 75 nm thick V 2 O 5 fi lms deposited on glass, after an annealing step of 1 h at 773 K, in air. The V 2 O 5 fi lms are also deposited and optimized on polyimide substrates, but lower annealing temperature is required, 573 K for 3 h, to maintain the fl exibility of the substrate and simultaneously high Seebeck coeffi cient, −591 µV K −1 . These fi lms are used in a simple design sensor and tested on the surface of a microfl uidic channel (500 µm) made of polydimethylsiloxane, while having hot water fl owing through it. The response time is below 1 s and the recovery time around 5 s.

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

“…Sensor sensitivity refers to the ratio of the change ∆ y of the system response under static conditions to the corresponding input change ∆ x , that is, the ratio of the dimensions of output and input. When the sensor output and input dimensions are the same, the sensitivity can be understood as the magnification [ 21 , 174 , 175 ]. The temperature coefficient of resistance TCR (TCR, in ) of the common resistance type flexible temperature sensor is expressed in the following expression, , is the relative resistance change ( ) as a function of temperature, where represents TCR.…”

“…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 ].…”

Recent Progress of Self‐Powered Sensing Systems for Wearable Electronics

“…Thus, a wearable temperature sensor can be used to improve the precision of temperature detection for healthcare and medical applications . In fact, many types of wearable temperature sensors using composite materials, diodes, or metal layer patterned on flexible substrates have been applied in flexible electronic applications . However, many challenges still remain for the wearable temperature sensing application: (1) interferences form the external environment, such as various gases, different humidity and light, (2) accurate and stable detection of temperature under human motion, and (3) achievement of high‐resolution temperature distribution using sensor array.…”

Multifunctional Skin‐Inspired Flexible Sensor Systems for Wearable Electronics

“…As the kernel of IoTs, wearable electronic skin (E‐skin) devices take the predominant role in seamlessly interfacing among surroundings and individuals by virtue of integrated flexible sensor systems based on wireless network connectivity. Huge efforts, in the past decade, have thus been dedicated to developing versatile human‐interactive devices via imitating skin‐like functions, such as tactile, humidity, or temperature sensing capabilities, contributing to diverse intriguing applications (e.g., soft robotics, medical devices) . Despite state‐of‐the‐art bulk‐based planar integrated‐circuit devices, their rigid and brittle nature gives rise to the incompatibility with curvilinear and soft human bodies, restricting the development of newborn human‐friendly interactive electronics.…”