Biomedical sensors are special electronic devices that can transduce biomedical signals into easily measurable electric signals. Biomedical sensors are the key component in various medical diagnostic instruments and equipment.

Biomedical sensors have been widely applied in medical image analysis and diagnostics, portable and clinical diagnostics, and laboratory analytical applications.

Biomedical sensors are usually classified according to the quantity to be measured and are typically categorized as physical, electrical, or chemical, depending on their specific applications.

pulse oximeter sensors are small non-invasive devices that are attached to a person’s finger, or other appendages, to measure blood oxygen saturation (SpO2) and heart rate. These sensors determine how efficiently oxygen is being carried through the body by the bloodstream. There are different variations of pulse oximeter sensors that attach to fingers, ears or toes and, in the case of veterinary applications, on the tongue.

Optical heart-rate monitors are the most common pulse sensors in wearables. Most of them glean heart-rate data through “photo plethysmography” (PPG), or the process of using light to measure blood flow. Wearables with optical heart-rate monitors have small LEDs on their undersides that shine green light onto the skin on your wrist. The different wavelengths of light from these optical emitters interact differently with the blood flowing through your wrist. When that light refracts (or reflects) off your flowing blood, another sensor in the wearable captures that information. That data can then be processed, along with motion information detected by the device’s accelerometer, with algorithms to produce understandable pulse readings.