Wearable sensorfor real-time, continuous monitoring of vital signs


The more people move, the more difficult it is to accurately monitor physiological parameters such as heart rate, oxygen levels, respiration and blood pressure.

Most progress has been made in the area of portable heart rate monitors, where the highest level of reliability is found with devices that use a ECG chest strap transmitter to gather heart rate data. These can be used under a wide spectrum of different types of movement, but they can be uncomfortable and sometimes impractical to use on a routine basis.

More user-friendly approaches have emerged based on the use of photoplethysmography (PPG), an optical approach that can measure multiple and critical parameters in addition to heart rate and lends itself to miniaturisation, as seen in the emergence of smart watches with inbuilt heart rate measurement.

The drawback with conventional PPG is that the sensor may be confused by body motion resulting in innacurate readings.

For the past decade, researchers in the Photonics Engineering & Health Technology Research Group in the Wolfson School of Mechanical, Electrical and Manufacturing Engineering have been developing the optoelectronic sensor technologies

Carelight’s patented novel optical layout aims to overcome the limitations of PPG sensors to continuously deliver a clear signal, even in high intensity physical activity. The ultra-lightweight PPG sensor could be placed on various parts of the body to provide reliable, continuous monitoring of a range of vital signs including Heart Rate, Respiration Rate, Heart Rate Variability, Blood Pressure, Temperature and Oxygenation levels.

The Carelight sensor is being developed to rely on a novel combination of characteristics

Design layout
incorporates multiple copies of illumination sources and several different wavelengths to allow for different skin types, colours, ages

Automatic selection
selects optimum illumination source / wavelength combination for the best quality signal at each illumination interval

Additional functionality
design incorporates additional sensor devices, for example an accelerometer and temperature sensor