Taking into account the size of the various electronic components we have to include in the wearable, and the constraints associated with the sensors, we have decided to focus on a foot wearable. The sensors will be placed on the top and bottom of the foot thanks to a textile sock/bracelet part. The rest of the components (battery, wifi and micro chip) will be held in an ankle or thigh bracelet.

Because we have not yet settled on the exact battery, wifi module and micro chip we want to use, we focussed first on the sensors part of our wearable.

Below are photos of our first, very rough prototype. For each sensor, we are using a made-to-fit 3D-printed plastic case. Right now it is hard plastic but ideally, it would be made of medical-grade silicon.

A window of the size of the case is cut into a thick slightly elastic fabric A. The case is placed in this window. Both the thick textile A and the case are sewn onto a thinner and more elastic textile B. [See diagram below, top is the view from the inside and bottom is a longitudinal cut]

We placed the temperature sensor above the foot because it was slightly smaller and did not require contact, and the heart-rate and SPO2 sensor below it on the flatter sole part. We added a short elastic strap around the ankle to maintain the whole thing in place.