The global incidence rate of respiratory diseases continues to rise, and efficient diagnostic tools are urgently needed. Although current wearable devices can monitor bodily fluids such as sweat and saliva, continuous sampling and analysis of exhaled breath condensate (EBC) still face challenges - it is difficult to obtain stable EBC samples in daily activities. Especially for patients with respiratory alkalosis (often accompanied by dizziness and fainting), clinical assessment of blood acid-base imbalance relies on invasive arterial blood gas analysis (ABC), but frequent blood collection is not feasible. As an early pathological signal, respiratory rhythm disorder generates weak air pressure (often below 0.3 Pa) that exceeds the detection limit of traditional pressure sensors.

Professor Ren Jie's team of Tongji University has developed a wearable mask based on ion gel microneedles (IMN-1/2), which realizes ultra-low pressure sensing (0.3 Pa) and ultra-high sensitivity (2980.23 kPa ⁻⁻) through pyramid shaped microarray structure. This device integrates a printed circuit board (PCB) and a Bluetooth module, which can wirelessly transmit respiratory pressure, frequency, and mode data, while using pH responsive fluorescent crosslinking agents to monitor changes in EBC acidity and alkalinity. The amphiphilic properties of microneedles (balance between hydrophilic monomer DMAA and hydrophobic ionic liquid [t-Bu ₄] TFSI) enable controllable water absorption while limiting swelling, ensuring long-term conductivity stability. What is even more groundbreaking is that its strong adhesion can seal the mask valve, enhance CO ₂ re inhalation through physical barrier, directly regulate the pH value of the patient's arterial blood, and achieve integrated diagnosis and treatment.

Innovative Design and Core Performance

Micro needles are prepared by custom PDMS mold photopolymerization, with a transparent light yellow pyramid structure (needle height 830 μ m) and gradient pores (2.8-7.9 nm). The finite element simulation (Fig. 2f) shows that the deformation rate of IMN-1/2 reaches 13.6% under the pressure of 0.5 Pa, while the traditional ion gel (IG-1/2) has almost no response. This deformation amplification effect originates from the extremely small contact area at the tip of the microneedle, significantly shortening the ion migration path. The parental design reduced the contact angle of the microneedle from 102.7 ° to 41.9 ° within 10 minutes (Figure 2h), and stabilized the water absorption rate at 1.6% (Figure 2i), avoiding leakage of ionic liquid caused by swelling.