Reverse Haptic Alerting: Human‐Centered Intelligent Systems That Turn Chemical and Biomedical Signals Into Felt Cues

Wearable chemical and biomedical sensors have advanced rapidly, yet most still communicate through color change, an electrical readout, or a smartphone alert. These channels can become unreliable precisely when they are needed most: Under personal protective equipment (PPE), in noise, or during cognitive overload. This Perspective argues for inverting the usual information flow. Instead of converting touch into data, as tactile sensors and electronic skins do, it converts a chemical or biological signal into a stimulus felt through skin mechanoreceptors. The field is framed as an intelligent, human‐centered sensing architecture along three axes: the target signal (from sweat biomarkers to chemical‐warfare agents (CWAs)), the stimuli‐responsive transduction mechanism, and the body site at which the cue is perceived. Because tactile acuity varies more than tenfold across the body, placement is treated as a primary design variable. A machine‐learning (ML) layer is then proposed that builds a personalized digital twin of the wearer’s tactile perception and, in a closed loop, recommends where to place a sensor and how to actuate it, raising detection while keeping stimulus, discomfort, and false alarms low. An illustrative synthetic case study demonstrates the detection–discomfort trade‐off, and the required datasets and experiments are outlined.