In this work, we report an active respiration monitoring sensor based on a piezoelectric-transducer-gated thin-film transistor (PTGTFT) aiming to measure respiration-induced dynamic force in real time with high sensitivity and robustness. It differs from passive piezoelectric sensors in that the piezoelectric transducer signal is rectified and amplified by the PTGTFT. Thus, a detailed and easy-to-analyze respiration rhythm waveform can be collected with a sufficient time resolution. The respiration rate, three phases of respiration cycle, as well as phase patterns can be further extracted for prognosis and caution of potential apnea and other respiratory abnormalities, making the PTGTFT a great promise for application in long-term real-time respiration monitoring.

This paper addresses a wearable piezoelectric energy harvester that combines a PVDF piezoelectric charge generator with an a-Si:H dual-gate thin-film transistor as a rectifier. An analytical model and equivalent circuit elaborate their working principle and device physics. A preliminary experimental study proves the device concept and demonstrates that such a harvester is capable of generating microwatt-range power with a simple 90° finger bending action. Coupled with low-cost and large-area fabrication processes, a pixelated energy-harvesting array can be potentially achievable, making it a promising alternative to energy sources for wearable electronics.

Tactile sensors that acquire force and temperature information are key to machine tactile intelligence. In this article, an active tactile sensor incorporating an array of 3-D field-coupled thin-film transistors (FCTFTs) with a 4 x 4 pixelated polyvinylidene fluoride (PVDF)-based force and temperature sensors is studied. In order to enhance sensitivity and reduce power consumption, a 3-D FIN-shaped FCTFT is designed and a subthreshold operation is implemented. We have demonstrated its functions in human-machine interfacing, object characterization and recognition, force and temperature mapping, and dynamic force tracing. Such a tactile sensor array is promising for applications in machine tactile intelligence and humanoid robotics.

The use of radio frequency identification (RFID) technology for the automatic identification and communication of physical parameters with on board integrated sensor attracts vast applications on a large scale ranging from mobile healthcare to logistics, supply chains, robotics and many others. Recently, sensor RFID tags have been considered in wearable electronics. However, these devices are still empowered by a battery. In this paper, we proposed and designed a self-sustainable sensor integrated RFID tag for wearable electronics applications. A polyvinylidene fluoride (PVDF) integrated dual-gate thin film transistor (TFT) was used to harvest energy from daily human activities such as arm/finger movements. Numerical analysis and preliminary results of such energy harvester was reported in addition to system design of sensor integrated chip-based active RFID tag.

Internal browning (IB)-related disorders in apples are causing significant economic losses, as they undermine consumer trust and market acceptability. Especially for susceptible cultivars, a comprehensive assessment of IB across the whole supply chain is crucial to meet consumer demand and trust, reduce food waste, and improve the profit margins of producers. To address these objectives, there is an urgent need for a fast, reliable, and portable nondestructive technique that enables real-time decisionmaking. In this study, apples were harvested early and late from two orchards and stored under two different conditions. After seven months storage, a representative sample of apples were analyzed using electrical impedance spectroscopy (EIS) to assess IB, categorizing the samples into healthy, slight brown, and severe brown. To validate the EIS results, a standard quality parameter, fruit firmness, was analyzed. The EIS spectrum shows that the magnitude in the lower frequency range (40 Hz to 1.4 kHz) and phase in mid-frequency range (1.4 to 15 kHz) yields the most promising results, with statistically significant differences (p $\leq$ 0.001) and (p $\leq$ 0.005), respectively. Contrarily, firmness measurement did not exhibit promising discrimination between healthy and internally browned apples (p-value of 0.21). Furthermore, the EIS spectrum of the three different classes were fitted using a single Cole equivalent model, revealing its efficacy as the best-fit equivalent circuit and offered valuable insights into the physio-chemical changes in biological cells. This work solidifies the EIS potential as a powerful tool for real-time, nondestructive, user-friendly, and cost-effective method in sustainable precision agriculture and food security assessment.

This letter reports on a dual-mode wearable energy harvester that utilizes both piezoelectric and photoelectric effects. It integrates a piezoelectric transducer with a 3-D photosensitive dual-gate thin-film transistor (DGTFT) as a rectifier and a buffer. The energy conversion efficiency is enhanced by reducing the internal resistance of the 3-D photosensitive DGTFT upon light illumination. Such a dual-mode energy harvester is promising for wearable electronics.