A highly sensitive flexible capacitive pressure sensor with hierarchical pyramid micro-structured PDMS-based dielectric layer for health monitoring

Non-Secondary Activating Flexible Liquid Metal Sensors with Excellent Waterproof Capability for Detection of Human Signals

In recent years, flexible sensors have gained increasing attention due to their excellent flexibility. Liquid metal (LM) has gradually become an ideal material for fabricating flexible sensors, thanks to its outstanding electrical conductivity and low-temperature fluidity. However, oxidation and the need for secondary activation of LM present significant technical challenges in the development of flexible LM sensors. In this paper, we introduce a simple method that integrates the flexibility of polydimethylsiloxane (PDMS) to fabricate flexible LM sensors with a sandwich structure. The sandwich-structured sensor demonstrates superior conductivity and effectively prevents LM oxidation and the need for secondary mechanical activation. Additionally, the PDMS-LM sensor exhibits excellent performance under various conditions, with a fast response time to mechanical stimuli (0.5 s), as well as outstanding durability and stability (>10,000 s of cycling). These remarkable properties give the sandwich PDMS-LM sensor great potential for the field of human motion monitoring, bringing further development and direction for intelligent sensing technology.

Self-Powered Biomimetic Pressure Sensor Based on Mn-Ag Electrochemical Reaction for Monitoring Rehabilitation Training of Athletes

Self-powered pressure detection using smart wearable devices is the subject of intense research attention, which is intended to address the critical need for prolonged and uninterrupted operations. Current piezoelectric and triboelectric sensors well respond to dynamic stimuli while overlooking static stimuli. This study proposes a dual-response potentiometric pressure sensor that responds to both dynamic and static stimuli. The proposed sensor utilizes interdigital electrodes with MnO2/carbon/polyvinyl alcohol (PVA) as the cathode and conductive silver paste as the anode. The electrolyte layer incorporates a mixed hydrogel of PVA and phosphoric acid. The optimized interdigital electrodes and sandpaper-like microstructured surface of the hydrogel electrolyte contribute to enhanced performance by facilitating an increased contact area between the electrolyte and electrodes. The sensor features an open-circuit voltage of 0.927 V, a short-circuit current of 6 µA, a higher sensitivity of 14 mV/kPa, and outstanding cycling performance (>5000 cycles). It can accurately recognize letter writing and enable capacitor charging and LED lighting. Additionally, a data acquisition and display system employing the proposed sensor, which facilitates the monitoring of athletes' rehabilitation training, and machine learning algorithms that effectively guide rehabilitation actions are presented. This study offers novel solutions for the future development of smart wearable devices.