We report the excellent sensing performance and health detecting applications of a flexible capacitive pressure sensor based on a Ti ₃ C ₂ T _x (MXene)/polyvinyl pyrrolidone (PVP) composite nanofiber membrane.

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.

In recent years, flexible pressure sensors have become an important part of soft electronics due to their tactile sensing abilities. However, manufacturing pressure sensors with high sensing performance and excellent applicability is still a great challenge. In this paper, we report the fabrication, sensing performance and applications of a flexible capacitive pressure sensor based on a polyvinyl pyrrolidone (PVP) nanofiber membrane (NM), which has a better biocompatibility and a wider applicability than the traditional dielectric layer materials. The cost-effective process of electrospinning and an ultra-violet (UV) photochemical aftertreatment are employed to prepare a PVP NM, which contribute to improving the performance of the sensor. The experimental results show that our sensor exhibits a fast response/recovery time (41/36 ms), a high sensitivity (0.278 kPa⁻¹ at 0–2 kPa), a wide pressure range (0–200 kPa), an ultra-low detection limit (∼50 Pa) and an excellent stability (8000 cycles). Thanks to its superior performance, the sensor can be used to monitor various subtle physiological and physical signals, such as pulse rate, respiration, mouse clicks, body movement and air flow. In addition, a 4 × 4 sensor array is fabricated that can map objects with various geometries, which demonstrates its ability to accurately identify the spatial pressure distribution. The developed high-performance and wide-applicative flexible sensor can provide new opportunities for innovative applications of advanced human–computer interface systems.

Herein, a flexible pressure sensor with high sensitivity was created using a dielectric layer featuring a hierarchical pyramid microstructure, both in simulation and fabrication. The capacitive pressure sensor comprises a hierarchically arranged dielectric layer made of polydimethylsiloxane (PDMS) with pyramid microstructures, positioned between copper electrodes at the top and bottom. The achievement of superior sensing performance is highly contingent upon the thickness of the dielectric layer, as indicated by both empirical findings and finite-element analysis. Specifically, the capacitive pressure sensor, featuring a dielectric layer thickness of 0.5 mm, exhibits a remarkable sensitivity of 0.77 kPa^-1 within the pressure range below 1 kPa. It also demonstrates an impressive response time of 55 ms and recovery time of 42 ms, along with a low detection limit of 8 Pa. Furthermore, this sensor showcases exceptional stability and reproducibility with up to 1,000 cycles. Considering its exceptional achievements, the pressure sensor has been effectively utilized for monitoring physiological signals, sign language gestures, and vertical mechanical force exerted on objects. Additionally, a 5 × 5 sensor array was fabricated to accurately and precisely map the shape and position of objects. The pressure sensor with advanced performance shows broad potential in electronic skin applications.

This paper presents a microwave microfluidic biosensor for monitoring blood glucose levels. The glucose sensor is a triple ring microstrip patch antenna integrated with a biomimetic microfluidic device capable of measuring a fixed volume of glucose solution. The sensor was utilized to detect 50–500 mg/dL glucose solutions. The interaction of the glucose solution with the electromagnetic field on the patch's surface influences both the resonance frequency and the magnitude of reflection coefficient. The results indicate that the microfluidic device can reduce experimental error and enhance the correlation between glucose concentration, resonant frequency, and reflection coefficient. Finally, the microfluidic sensor had a sensitivity of 0.25 MHz/(mg/dL), a detection limit as low as 7.7 mg/dL, and correlation coefficients of resonance frequency and reflection coefficient with a glucose concentration of 0.996 and 0.984, respectively. The experiment on the sensor's stability verifies the sensor's excellent stability and rapid response (~ 150 ms). Consequently, the device can be used to differentiate the concentration of glucose solutions, as well as to detect blood glucose levels at an early stage.