Towards Wearable and Flexible Sensors and Circuits Integration for Stress Monitoring

Abstract

Excessive stress is one of the main causes of mental illness. Long-term exposure of stress could affect one's physiological wellbeing (such as hypertension) and psychological condition (such as depression). Multisensory information such as heart rate variability (HRV) and pH can provide suitable information about mental and physical stress. This paper proposes a novel approach for stress condition monitoring using disposable flexible sensors. By integrating flexible amplifiers with a commercially available flexible polyvinylidene difluoride (PVDF) mechanical deformation sensor and a pH-type chemical sensor, the proposed system can detect arterial pulses from the neck and pH levels from sweat located in the back of the body. The system uses organic thin film transistor (OTFT)-based signal amplification front-end circuits with modifications to accommodate the dynamic signal ranges obtained from the sensors. The OTFTs were manufactured on a low-cost flexible polyethylene naphthalate (PEN) substrate using a coater capable of Roll-to-Roll (R2R) deposition. The proposed system can capture physiological indicators and data be interrogated by Near Field Communication (NFC). The device has been successfully tested with healthy subjects, demonstrating its application for real-time stress monitoring.

Feasibility of Ultra-Short-Term Analysis of Heart Rate and Systolic Arterial Pressure Variability at Rest and during Stress via Time-Domain and Entropy-Based Measures

“…Furthermore, more recently developed entropy-based measures permit the assessment of the regularity and complexity of cardiovascular dynamics [ 18 , 19 , 20 , 21 , 22 ]. ST HRV analysis has also been proven useful outside clinical settings, e.g., to monitor health and wellbeing at home and in everyday life scenarios using wearable smartwatches and smartbands [ 23 , 24 , 25 , 26 ].…”

Source-Degenerated Schmitt-Trigger-Based High-Performance Digital Logic for Flexible Organic Thin-Film Transistor Technologies

“…1(b)). Organic-TFT-based integrated circuits that have been reported to date include data converters [1], [2], DC-DC converters [3], radio-frequency identification (RFID) tags [4], [5], sensors and sensor interfaces [6]- [11], static random access memories (SRAM) [12], [13], hardware security [14], Internet of Things applications [15], and biomedical sensors and signal front-ends [16]- [19]. Masoud The fabrication process of p-channel organic TFTs with adequate performance and stability has advanced quite far.…”

Feasibility of Ultra-Short Term Analysis of Heart Rate and Systolic Arterial Pressure Variability at Rest and During Stress via Time-domain and Entropy-based Measures

“…With the widespread adoption of wearable biomedical devices especially in domestic settings (e.g. smart-healthcare), the research is now focusing on whether and to what extent shorter recordings can be exploited for cardiovascular variability analysis, given their lower computational and memory resources, in order to quickly extract useful physiological indexes [25,26,29,30]. Several works have recently investigated on the so-called ultra-short term (UST) HRV analysis which exploits recordings shorter than 5 minutes, comparing the results with those obtained using the ST gold standard [31][32][33][34][35][36].…”

“…ST HRV analysis has been proven useful also outside clinical settings, e.g. to monitor health and wellbeing at home and in everyday life scenarios using wearable smartwatches and smartbands [25][26][27][28].…”