**Non-Invasive Electrochemical Biosensors Operating in Human Physiological Fluids**

**Magnus Falk 1, Carolin Psotta 1,2, Stefan Cirovic 1 and Sergey Shleev 1,2,\***


Received: 10 October 2020; Accepted: 4 November 2020; Published: 7 November 2020

**Abstract:** Non-invasive healthcare technologies are an important part of research and development nowadays due to the low cost and convenience o ffered to both healthcare receivers and providers. This work overviews the recent advances in the field of non-invasive electrochemical biosensors operating in secreted human physiological fluids, viz. tears, sweat, saliva, and urine. Described electrochemical devices are based on di fferent electrochemical techniques, viz. amperometry, coulometry, cyclic voltammetry, and impedance spectroscopy. Challenges that confront researchers in this exciting area and key requirements for biodevices are discussed. It is concluded that the field of non-invasive sensing of biomarkers in bodily fluid is highly convoluted. Nonetheless, if the drawbacks are appropriately addressed, and the pitfalls are adroitly circumvented, the approach will most certainly disrupt current clinical and self-monitoring practices.

**Keywords:** non-invasive biosensors; human physiological fluids; tears; sweat; saliva; urine
