Enabling Real-Time Monitoring of Wound Exudate Status through On-Tag RF Computing

RF computing represents an emerging paradigm that computes by directly manipulating physical-layer RF signal properties. Capitalizing on this, we present a battery-free wireless system for real-time pH monitoring in diabetic foot ulcers (DFUs). Our core innovation lies in hardware co-design that implements on-tag RF computing. This is achieved by integrating pH-sensitive hydrogel as a functional antenna component to directly modulate backscattered signals. This enables direct chemical-to-RF transduction: pH shifts instantaneously modulate antenna impedance, thereby altering the phase of backscattered signals. To ensure robustness, we use a differential twin-tag architecture to suppress environmental interference, which enables precise pH extraction. By embedding sensing within passive RF hardware, we deliver a low-cost solution advancing mobile health through RF computing principles.