Flexible Humidity and Pressure Sensors Realized by Molding and Inkjet Printing Processes with Sandwich Structure

Abstract

Flexible and wearable devices are important parts toward the realization of artificial intelligence and have an irreplaceable advantage over traditional rigid sensors. In this work, a film with double surface structure is prepared by using sandpaper and the leather with a rhombic structure as a mold, thereby obtaining a sandwich structure resistive type pressure sensor, which has high sensitivity (77.78 kPa−1, 24 Pa minimum detection) and wide detection range (0.024–230 kPa). The sensors have fast response time (30 ms) and high reliability over 5000 repetitive cycles. The humidity sensor is printed on the top layer of the sensor by using screen printing and inkjet printing technique, and the sandwich structure humidity and pressure sensor is obtained. The humidity sensors show the sensitivities of 0.137/%, 1.57/%, and 11.145/% in the relative humidity range from 25 to 55%, 55 to 70%, and 70 to 80%, respectively. Such sensors not only have excellent capabilities in pressure and humidity detection, but also avoid the complex process of multiple single‐function devices stacked on each other. The applications of sensors in monitoring artery pulse waves, detecting spatial pressure distribution, and sweat is demonstrated.

Macromolecule Relaxation Directed 3D Nanofiber Architecture in Stretchable Fibrous Mats for Wearable Multifunctional Sensors

“…This is likely due to the better swelling or dissolving effect of these solvents on TPU macromolecular chains, resulting in a change of PtNPs distribution on TPU surface (Figure d), and even the sensor has incomplete recovery of resistance in contacts with the DMF vapor. Hence, the TP-60 sensor is promising as a comfortable, safe, and high-quality sensor for monitoring multiple stimuli, which is overall superior to other multiresponsive sensors (Table S2) if considering simple material choice and fabrication technology. ,,,,,, …”

Recent Advances in Carbon Material‐Based Multifunctional Sensors and Their Applications in Electronic Skin Systems

“…Besides, Maimaitiyiming and coworkers demonstrated GO-based humidity and SWCNTsbased pressure sensor with the sandwich structure at the same time, of which SWCNTs were the electrodes of these two sensors, as shown in Figure 4d. [127] They were designed by applying screen printing and inkjet printing processes, respectively, and using sandpaper and leather with a rhombic structure as molds. It has successfully detected various human activities, including pulse, breathing, and palm sweat.…”

“…d) Diagram of the humidity sensing section (upper left) and pressure sensing section (bottom left) of the dual-modal sensor. Reproduced with permission [127]. Copyright 2020, Wiley-VCH.…”

A Highly Sensitive, Breathable, and Biocompatible Wearable Sensor Based on Nanofiber Membrane for Pressure and Humidity Monitoring

“…In this regard, extensive investigations on new sensing materials, simple and low-cost manufacturing methods, environment-friendly preparation processes, and multi-functional integration have been conducted for wearable humidity sensors. [15][16][17] Humidity sensors usually transduce environmental humidity and human physiological state into electrical signals, which are mainly categorized into resistance type and capacitive type based on the mechanisms. Moisture-sensitive materials in humidity sensors are essential and can interact with water molecules.…”