High‐performance piezoresistive sensors based on transfer‐free large‐area PdSe₂ films for human motion and health care monitoring

Abstract

Two‐dimensional transition metal dichalcogenides (TMDs) are needed in high‐performance piezoresistive sensors due to their strong strain‐induced bandgap modification and thereby large gauge factors. However, integrating a conventional high‐temperature chemical vapor deposition (CVD)‐grown TMD with a flexible substrate necessitates a transfer process that inevitably degrades the sensing properties of the TMDs and increases the overall fabrication complexity. We present a high‐performance piezoresistive strain sensor that employs large‐area PdSe2 films grown directly on polyimide (PI) substrates via plasma‐assisted selenization of a sputtered Pd film. The reliable strain transfer from the substrate to the PdSe2 film ensures an outstanding strain‐sensing capability of the sensor. Specifically, the sensors have a gauge factor of up to 315 ± 2.1, a response time under 25 ms, a detection limit of 8 × 10−6, and an exceptional stability of over 104 loading–unloading cycles. By attaching the sensors to the skin surface, we demonstrate their application for measuring physiological parameters in health care monitoring, including motion, voice, and arterial pulse vibration. Furthermore, using the PdSe2 film sensor combined with deep learning technology, we achieved intelligent recognition of artery temperature from arterial pulse signals with only a 2% difference between predicted and actual temperatures. The excellent sensing performance, together with the advantages of low‐temperature fabrication and simple device structure, make the PdSe2 film sensor promising for wearable electronics and health care sensing systems.image

Grain‐Boundary‐Rich RuO2 Porous Nanosheet for Efficient and Stable Acidic Water Oxidation

“…In Raman spectra (Figure 2a), the typical characteristic peaks centered on 512, 630 and 702 cm −1 in Com‐RuO 2 belong to the vibration modes E g , A 1g and B 2g respectively [10] . It is worth noting that after introducing abundant of GBs, the wave numbers of the three characteristic peaks of GB‐RuO 2 (501, 617, and 680 cm −1 ) decrease significantly compared with Com‐RuO 2 , which means that the vibration frequency of Ru−O is weakened and the spatial distance of Ru−O bond is lengthened [22–24] . This result is consistent with the XRD and HRTEM, which further proves that rich grain boundaries lead to surface tensile stress and provides a possibility for modulating RuO 2 ’s electronic structure.…”

High-Speed Self-Powered PdSe2/Si 2D-3D PIN-like Photodetector with Broadband Response Based on PdSe2 Quantum Island Structure

“…It is demonstrated that the first three vibration modes originate from the motion of Se atoms, and the A g 3 mode comes from the relative motion between Pd and Se atoms. 24 The XPS results are presented in Figure 1d,e.…”

Differential pressure sensors based on transfer-free piezoresistive layered PdSe2 thin films

“…which is well compatible with the BEOL silicon circuit integration [24]. These achievements suggest that it is promising for strain sensors [25]. However, to the best of our knowledge, their pressure sensor that can be integrated into the MEMS platform has not yet been reported.…”

“…The Pd film was subsequently selenized by PES to obtain a polycrystalline PdSe 2 film at 200 °C. Notably, the low temperature is also compatible with widely used polyimide (PI) substrate, suggesting great potential for flexible devices [25]. Finally, the 5 nm Cr/50 nm Au electrodes were deposited by thermal evaporation.…”