Flexible Smart Noncontact Control Systems with Ultrasensitive Humidity Sensors

Abstract

The development of noncontact humidity sensors with high sensitivity, rapid response, and a facile fabrication process is urgently desired for advanced noncontact human–machine interaction (HMI) applications. Here, a flexible and transparent humidity sensor based on MoO3 nanosheets is developed with a low‐cost and easily manufactured process. The designed humidity sensor exhibits ultrahigh sensitivity, fast response, great stability, and high selectivity, exceeding the state‐of‐the‐art humidity sensors. Furthermore, a wearable moisture analysis system is assembled for real‐time monitoring of ambient humidity and human breathing states. Benefiting from the sensitive and rapid response to fingertip humidity, the sensors are successfully applied to both a smart noncontact multistage switch and a novel flexible transparent noncontact screen for smart mobile devices, demonstrating the potential of the MoO3 nanosheets‐based humidity sensors in future HMI systems.

Electrostatic self-assembly enabled flexible paper-based humidity sensor with high sensitivity and superior durability

“…Humidity is one of the essential indexes of air, which is important for industrial and agricultural production and our daily life. As a humidity detection tool, flexible electronic humidity sensors have attracted much attention because of their wide applications in fields of wearable electronics, smart textiles, electronic skin, and soft robotics [12] , [13] , [14] , [15] , [16] , [17] , [18] , [19] , [20] . Specifically, conductive polymer composite-based humidity sensors with incorporated electrically conductive fillers in insulating polymer matrixes are attracting much attention owing to their excellent flexibility, low cost, and ease of processing [21] , [22] , [23] , [24] , [25] , [26] , [27] .…”

Recent Advances in Nanomaterial‐Enabled Wearable Sensors: Material Synthesis, Sensor Design, and Personal Health Monitoring

“…[ 124 ] For example, Yang et al reported a wearable sensor based on MoO 3 nanosheets to monitor water molecule. [ 115 ] As shown in Figure , indium tin oxide (ITO) interdigitated electrodes were deposited on PET film and the MoO 3 nanosheet solution was spin‐coated onto the surface of ITO interdigitated electrodes. The adsorption of water molecule on the MoO 3 would increase the conductivity.…”

Soft Electronics for the Skin: From Health Monitors to Human–Machine Interfaces

“…[205] Furthermore, HMI devices based on TENGs have been developed for both noncontact and tactile interaction. [196,206,207] Breath-based HMIs have been developed by Mao et al to realize household object control which is schematically illustrated in Figure 11a. [196] The TENG was activated by the breathing of the user and the signals were processed and transmitted to the appliance (Figure 11b).…”

“…Other types of sensors can be used for noncontact interaction. [207] Additionally, TENGs have also been implemented for tactile usage. A washable electronic textile (WET) comprised of two layers of fabric (silk and nylon) that sandwiched a printed layer of PU/CNT electrodes has been developed.…”