Wearable sensor for 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.


Carelight’s novel optical layout overcomes well-documented limitations of PPG sensors to continuously deliver a clear signal, even in high intensity physical activity. The ultra-lightweight wearable PPG sensor can 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 relies 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




Carelight technology is aimed at the emerging markets for wearable technologies and provides the opportunity for affordable, continuous monitoring of vital signs without the need for extensive technical equipment, or to compromise normal daily activity during measurements.


Sensor products developed around Carelight technology offer a number of benefits over existing technologies that will appeal to a range of sectors:


wellbeing and sports fitness                              in-patient care

recovery at home                                                hazardous environments


military personnel                                                independent living




Our prototype has been tested on 16 subjects at rest and on a treadmill at various speeds. The results demonstrate that it is possible to collect accurate PPG heart rate signals from the lower arm, at running speeds up to 14 km/hr. This accuracy trial showed that the PPG heart rate data collected from the Carelight system was highly correlated with ECG signals gathered in parallel from a Polar F1, chest strap heart rate monitor which is the current sport and fitness industry standard.


Various different sensors have been developed, using opto physiological modelling to determine the specific optical design requirements of different sites on the body.


Consideration has been given to scalable manufacturing methods such that sensors can be formatted for low cost disposable applications if required.


A patent application has been filed to protect the technology and Loughborough University is now looking for commercial partners to take the technology into regulated healthcare markets.


Dr Joanne Whitaker is happy to discuss the business development and IP aspects of the Carelight technology.


Read more http://www.lboro.ac.uk/enterprise/carelight/


Patent Information:
For Information, Contact:
Paul Burrows
IP Exploitation Manager
Loughborough University
Sijung Hu
Vincente Azorin-Peris
Innovative Technologies
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