Wearable sensors are compact devices integrated into clothing, accessories, or directly on the skin to continuously monitor physiological, biochemical, and environmental signals. They leverage advances in flexible electronics, microfabrication, and wireless communication to collect data unobtrusively during daily life, rather than only in clinical settings.

A major focus is on physiological monitoring. Flexible patches and smart textiles can track heart rate, electrocardiograms, respiration, movement, temperature, and blood oxygen saturation. These systems often use stretchable conductors and soft substrates so they conform to the body and maintain performance during motion. Motion sensors such as accelerometers and gyroscopes are widely used for activity recognition, gait analysis, fall detection, and rehabilitation assessment.

Another active area involves biochemical sensing through sweat, interstitial fluid, or tears. Researchers have demonstrated skin mounted platforms that measure electrolytes, metabolites like glucose and lactate, and other biomarkers in real time, sometimes integrating microfluidics to control sample collection. There is also progress in noninvasive or minimally invasive glucose monitoring that aims to support diabetes management without frequent finger pricks.

Energy supply and data transmission are critical challenges. Solutions include low power electronics, energy harvesting from motion or body heat, and compact rechargeable batteries. Wireless connectivity via Bluetooth or similar protocols enables continuous data streaming to smartphones or cloud platforms, where algorithms can analyze patterns and detect anomalies.

Key research directions include improving sensor accuracy and stability over long periods, enhancing comfort and biocompatibility, enabling multimodal sensing in a single platform, and addressing data privacy and security. Overall, wearable sensors are moving from prototypes toward integrated health and performance monitoring systems with broad applications in medicine, sports, and everyday wellness.