There has been some interesting news on the design of wearable medical devices recently. Rutgers University is developing a wristband that can access the blood stream and draw up samples via a micron-sized tube. Sensors on the band can count blood cells, bacteria, organic matter and particles in the air, providing the capability to monitor and process many more types of information than current wearables are able to do.
Another development is from Analog Devices. The company has created a platform device that medical device designers can use as a base to design upon. The device includes technology to support biopotential measurement, optical heart-rate measurement, bioimpedance measurement, motion tracking, and temperature measurement. It can be configured to mount to the body in various ways, on the wrist or strapped to the chest, for example. The device will allow testing various sensing technologies simultaneously, perhaps providing insights into correlation between different sensing modalities.
Both of the developments cited above are indicative of the focus that is being put on the design of wearables to move them into more widespread use as true medical devices.