Ultrabroad Pressure Sensing, Ultrasensitive, Multi‐Signal Ionogel‐Based Microneedles for Wearable Respiratory Health Monitoring

Abstract Developing wearable devices with high sensitivity, low‐pressure detection, and multi‐signal monitoring capabilities is critical for the effective diagnosis of respiratory diseases. Here, this work reports a wearable mask that integrates with a printed circuit board (PCB) and Bluetooth Low Energy (BLE) module, in tandem with ionogel‐based microneedle patches (IMN‐1/2) featuring a regularized microarray structure. By leveraging its gradient morphology, IMN‐1/2 achieves a pressure detection limit as low as 0.3 Pa and an ultrahigh sensitivity of 2980.23 kPa⁻¹ in low‐pressure range, enabling the effective monitoring of extremely weak breathing pressure signals. Moreover, hydrophilic N,N ‐dimethylacrylamide (DMAA) of IMN‐1/2 impart the patches with distinct amphiphilic characteristics that limited swelling while allowing for slow, controlled water absorption. When weakly alkaline exhaled breath condensate (EBC) permeates the IMN‐1/2 structure, it alters the charge state of cationic fluorescent crosslinkers, leading to a reduction in fluorescence intensity; this pH‐responsive behavior facilitated long‐term monitoring and potential diagnosis of respiratory alkalosis. Furthermore, the strong adhesion of IMN‐1/2 enhances the sealing integrity of IMN‐1/2‐integrated masks, physically restricting CO 2 inhalation and reducing arterial blood pH values of wearers, thus enabling physical therapy for respiratory alkalosis. This work demonstrates efficient ultralow‐pressure monitoring, expanding the diagnostic capabilities of piezo‐resistive pressure sensors through structural design.