After a turbulent half year, the importance of self-health monitoring increased considerably. The idea of bringing bioanalytical determinations at home to be done by everyone was a bit far from our reality but nowadays is more present than what we expected. In this context, I would like highlight in this blog some remarkable examples were biosensors, more precisely “wearable biosensors”, are developed and implemented with health purposes that define the first approaches of future perspectives.
The massive incorporation of smartphones in society led to propose their alternative use taking advantage of the powerful capacity of these portable platforms. Particularly, health care monitoring is considered one of the most interesting areas for implementing fast and reliable self-detection tools, and portable sensors show interesting results.
An important distinction must be done while considering a sensor “wearable” and is related to the invasive capacity on the end user. For biomedical applications, biosensors can be consider “invasive” when they require a physical disruptions over the organism (like sub-coetaneous implants or the use of needles) to measure and “non-invasive” when is not necessary to interfere any tissue to detect the analyte in the sample.
One interesting case is found on the wrist strap developed by predictor medical company to measure glucose in blood by near infrared spectroscopy and bioimpedance (https://www.prediktormedical.com/). This non invasive method aims to avoid the typical finger prick based test for patients with Diabetes offering an simple and fully automated alternative.
Abbot Freestyle Libre
On the other hand, Abbot presented a patch to sense glucose in interstitial fluids with an electrochemistry based approach. This user friendly device was approved by the FDA in US by 2018 and now is on the market at a price of 40 euros. The last version allows the integration with smartphones to scan the patch and monitor in real time the level of glucose in the user with a quick movement. Furthermore, this new patch includes a system of alarms to warn when the levels are out of the range.
Smart contact lens : Google and Novartis
One of the most famous cases was the smart contact lens announced by Google in 2014. The device wanted to detect glucose levels in tears offering a promising solution for diabetic patients. After an exhaustive development of a prototype, some clinical trials revealed not successful performance over this format and using tears as matrix was not the most adequate approach. The project was discontinued.
Alternatively, other example consisted in a radio frequency tri-layer sensor mounted on a tooth for remote assessment of food consumption. This sensor was placed over tooth enamel to monitor the composition of food and fluid ingestion. Future applications can include the detection of alcohol, sugars, salinity, pH and temperature.
Finally, an interesting idea was proposed in 2015 as the first temporary tattoo-based glucose sensor for noninvasive monitoring. This innovative way of sensing combine enzyme based amperometry over the epidermis to detect variations in glycemic levels due to food consumption. Even though, the article presents a proof of concept with further development it can be applied in plenty of different configurations.
Undoubtedly, great potential behind portable biosensors can be seen across the wide variety of possible configurations presented. The food smartphone project is based on the same principles that combine reliable analytical detection in a portable and friendly way.
Reference: Kim, J., Campbell, A.S., de Ávila, B.E. et al. Wearable biosensors for healthcare monitoring. Nat Biotechnol 37, 389–406 (2019). https://doi.org/10.1038/s41587-019-0045-y