NaCl Ionization-Based Moisture Sensor Prepared by Aerosol Deposition for Monitoring Respiratory Patterns

Abstract

A highly polarizable moisture sensor with multimodal sensing capabilities has great advantages for healthcare applications such as human respiration monitoring. We introduce an ionically polarizable moisture sensor based on NaCl/BaTiO3 composite films fabricated using a facile aerosol deposition (AD) process. The proposed sensing model operates based on an enormous NaCl ionization effect in addition to natural moisture polarization, whereas all previous sensors are based only on the latter. We obtained an optimal sensing performance in a 0.5 µm-thick layer containing NaCl-37.5 wt% by manipulating the sensing layer thickness and weight fraction of NaCl. The NaCl/BaTiO3 sensing layer exhibits outstanding sensitivity over a wide humidity range and a fast response/recovery time of 2/2 s; these results were obtained by performing the one-step AD process at room temperature without using any auxiliary methods. Further, we present a human respiration monitoring system using a sensing device that provides favorable and stable electrical signals under diverse respiratory scenarios.

High-Performance Flexible Humidity Sensors Based on MCl (M = Li, Na, K) Doped PVP/PVDF Self-Supporting Films for Boosted Real-Time Noncontact Moisture Monitoring

“…Humidity sensors are widely used in modern industrial fields such as agricultural planting, medical health monitoring, and soft robot control. − Humidity sensors can be divided into impedance, capacitance, quartz crystal microbalance, field effect transistor, and surface acoustic wave according to the parameters of measuring relative humidity (RH). Impedimetric humidity sensors are characterized by low cost, small size, and high interchangeability .…”

Highly Sensitive Interdigitated Capacitive Humidity Sensors Based on Sponge-Like Nanoporous PVDF/LiCl Composite for Real-Time Monitoring

“…The development of modern electronic devices has been intensified on a wide range to create a safe, comfortable, and energy-efficient environment. Humidity sensors are among the most widely used devices in daily life; for example, they have been used in biomedical applications, food processing, meteorology, agriculture, and health monitoring. − Humidity sensors can be classified as resistive, capacitve, quartz crystal microbalance, field effect transistor, and surface acoustic wave based on the parameters used for measuring relative humidity. Among the various types of humidity sensors, capacitive humidity sensors are commercially commonly used owing to their low power consumption and high output signals with a short response time. − However, the hindrance of the capacitive sensors is stability and sensitivity with the wide humidity detection ranges.…”

Humidity‐Driven Dynamic Based on Polystyrene‐Contained Gelatin (Gel‐PS) and PDMS Bilayer Wrinkling System

“…[11][12][13][14] At the macro-scale, external stimuli like heat, [15] humidity, [16][17][18] light, [19][20][21][22][23][24] and electromagnetic fields can be used to tune the transition between different reconfigurable structures. By extending these structures to the submicron scale, they can be applied in nanooptics, [25][26][27] microsensors, [28][29] and other fields. Consequently, constructing dynamically reconfigurable micro-/nano-hierarchical surfaces of polymeric material can dynamically control the infrared optical properties and multispectral camouflage of a material, which is key to achieving superstructures, metasurfaces, and smart materials.…”

“…This method generates buckling deformation caused by stress instability in bilayer wrinkling systems, making it simple, efficient, and easily scalable. [28][29] It is a general method for fabricating surface micro/nano patterns in recent years. It is important to note that the wrinkled patterns generated by stress instability are inherently dynamic, allowing for the real-time regulation of surface wrinkles by controlling stress release.…”