Humidity-Based Human–Machine Interaction System for Healthcare Applications

Abstract

Human–machine interaction (HMI) systems are widely used in the healthcare field, and they play an essential role in assisting the rehabilitation of patients. Currently, a large number of HMI-related research studies focus on piezoresistive sensors, self-power sensors, visual and auditory receivers, and so forth. These sensing modalities do not possess high reliability with regard to breathing condition detection. The humidity signal conveyed by breathing provides excellent stability and a fast response; however, humidity-based HMI systems have rarely been studied. Herein, we integrate a humidity sensor and a graphene thermoacoustic device into a humidity-based HMI system (HHMIS), which is capable of monitoring respiratory signals and emitting acoustic signals. HHMIS has a practical value in healthcare to assist patients. For example, it works as a prewarning system for respiratory-related disease patients with abnormal respiratory rates, and as an artificial throat device for aphasia patients. Achieved based on a laser direct writing technology, this wearable device features low cost, high flexibility, and can be prepared on a large scale. This portable non-contact HMMIS has broad application prospects in many fields such as medical health and intelligent control.

Skin-Attachable Sensors for Biomedical Applications

“…Metal oxides and nanomaterials are mainly used for respiratory humidity and temperature monitoring [ 49 , 50 ]. Sufficient hydrophilic groups and high specific surface area enable graphene oxide (GO) to monitor humidity.…”

An All-Fabric Tactile-Sensing Keypad with Uni-Modal and Ultrafast Response/Recovery Time for Smart Clothing Applications

“…Different e-textile humidity sensors are investigated in wearable applications. A flexible humidity sensor based on hydrophobic ionic liquid and polymer 19 or graphene oxide (GO) 20 was developed to realize non-contact tactility; however, the sensor's response and recovery time are in the order of several seconds. Additionally, the sensing mechanism depends on the capacitance variation, which can also be easily interfered by the ambient environments.…”

Ferroelectric Polarization and Oxygen Vacancy Synergistically Induced an Ultrasensitive and Fast Humidity Sensor for Multifunctional Applications

“…4−7 More importantly, humidity sensors can achieve touch-free communication with intelligent devices by sensing the water vapor emission from human metabolism. 3,8 For example, relying on the detection of finger-moisture evaporation, humidity sensors can realize the noncontact control of mobile devices. 3 It is worth noting that humidity sensors in noncontact operation avoid mechanical fatigue and bacterial/viral transmission, which have been notably superior to the direct contact sensors (pressure sensors, strain sensors, etc.)…”

“…With the arrival of the Internet of Things (IoT) and artificial intelligence (AI), humidity sensors have regained intensive research interest due to their important applications for smart wearable devices and noncontact human–machine interaction. − As one of the essential physiological activities for human beings, respiration provides important information for health conditions; thus, the real-time monitoring of breathing rate/depth is very necessary for special groups such as patients and athletes. By utilizing water vapor emission from human exhalation (relative humidity (RH) > 90%), a noncontact humidity sensor can be developed as a smart wearable device to easily meet the above requirements based on changing the frequency and amplitude of the electric signals. − More importantly, humidity sensors can achieve touch-free communication with intelligent devices by sensing the water vapor emission from human metabolism. , For example, relying on the detection of finger-moisture evaporation, humidity sensors can realize the noncontact control of mobile devices . It is worth noting that humidity sensors in noncontact operation avoid mechanical fatigue and bacterial/viral transmission, which have been notably superior to the direct contact sensors (pressure sensors, strain sensors, etc.)…”