Engineers have released designs for a 3D printed blood-oxygen sensor that can be made at home.

The Open Oximeter sensor has been developed by a team of engineers and scientists at the University of Bath.

It can be created by anyone with a 3D printer and basic electronic skills, and costs less than £10 to make.

Those behind the sensor, which is based on existing commercial devices, say it accurately monitors a person’s blood-oxygen levels.

It is worn on a finger clip and measures the reflection of different wavelengths of light, tracking the wearer’s heart rate and saturated percentage of oxygen.

The design – which comprises a sensor, readout electronics and software – has been published in the Journal of Open Hardware, with files shared on GitLab.

Professor Peter Wilson, from the University of Bath’s Department of Electronic and Electrical Engineering, said: “Monitoring blood-oxygen saturation has become a key part of patient care during the pandemic, with a particular focus on early warning of serious illness, so demand for pulse oximeters around the world is huge.

“We hope that, by sharing this open-source design, healthcare providers will be able to quickly produce more sensors at a reasonable cost.”

The team is now working with the University of Cambridge to develop low-cost artificial fingers, known as phantoms, that can be used to calibrate and validate oximeters.

These will also help to address the issue of racial bias in oximeters, which work more effectively for lighter-skinned people.

Dr Ben Metcalfe said: “The importance of accurate measurements cannot be overstated.

“A recent study in the New England Journal of Medicine identified quite clearly the racial bias present in current oximeters, which worryingly over-estimate the oxygen saturation among patients who identified their race as black.

“It is well known that calibration of pulse oximeters, especially for low levels of oxygen saturation seen in many Covid-19 patients, is technically challenging.

“By creating 3D printed materials with known optical properties we can develop phantoms that will enable calibration at these lower oxygen levels.”

The team received funding from the University of Bath’s alumni fund.