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Development of an epidermal microfluidic-based patch with an integrated all-carbon electrochemical sensor for glucose monitoring in sweat
1 , 1 , 2 , * 2
1  Biomedical Research Foundation of the Academy of Athens, Athens 11527, Greece
2  Institute of Nanoscience and Nanotechnology, NCSR “Demokritos”, Patriarhou Gregoriou & Neapoleos, 15310 Aghia Paraskevi, Greece
Academic Editor: Giovanna Marrazza


Wearable biosensors for the detection of analytes in sweat are an emerging and promising technology with important applications in monitoring a person’s physiological state. Sweat, being an easily accessible biofluid, shows great potential as a biological fluid for wearable devices, but also a number of challenges that must be addressed before a sensor can be commercialized. Herein, we present an epidermal patch type device, with an enzymatic electrochemical sensor for glucose monitoring and a microfluidic network for continuous sweat sampling. Detection of glucose in sweat removes the painful invasive blood sampling step of commercial devices, while paving the way for continuous monitoring of glucose levels. The microfluidic network was designed according to data acquired from microfluidic simulations using the COMSOL Multiphysics software package. A 3D-printed scaffold was used to transfer the network design to a PDMS layer, so that the patch could be attached to the user’s skin. The sensor’s electrodes were hand-drawn on a polyimide layer using conductive carbon ink. A dispersion of carbon black in a chitosan aqueous solution was subsequently drop-casted on the working electrode, followed by enzyme immobilization (glucose oxidase). The sensor was characterized in artificial sweat, taking into account the possible fluctuations of sweat pH, and was able to detect glucose in the range of 0.01 – 1 mM. The ability of the sensor to detect glucose was also tested using real samples of sweat.

Keywords: wearables; biosensors; nanotechnology; electrochemistry; glucose; sweat; microfluidics