Soft contact lens biosensor for in situ monitoring of tear glucose as non-invasive blood sugar assessment

Review on Micro- and Nanolithography Techniques and their Applications

“…In addition, sensor systems as well as flow strip chips for rapid diagnosis are also interesting applications. Blood glucose sensor microelectrodes integrated with a contact lens for continuous tear glucose monitoring [114], and a flow strip chip for detecting proteins derived from the blood of malaria parasites [115] are some examples.…”

Powering electronic contact lenses: current achievements, challenges, and perspectives

“…Drawing on the advances within nanotechnology, it has become technically feasible to fit electronics, for example, sensors, transmitters, amplifiers, and even displays, within the confinements of a standard-sized contact lens [5][6][7][8][9]. As regards sensors, they can be designed to gauge various features of biomarkers present in lachrymal fluid, while the complete circuitry arrangement, form factor, and opacity can be chosen not to impair vision.…”

“…Contact lenses are minimally invasive, and electronic lenses will offer real-time, non-traumatic biomarker probing, among many different possible applications. It should be emphasized, however, that whereas reports in popular media concerning smart contact lenses are stunningly impressive [1][2][3][4], actual, bona fide contact lens-based gadgets presented in the scientific literature are still quite far from real practical applications [5][6][7][8][9][10][11]. As the name implies, electronic circuitry relies on electric power, and even though the power demands of state-of-the-art micro-or even nano-electronics are minimal, some power is nonetheless needed.…”

“…While there is not much to say about the first approach [5,8,9], which is obviously a reasonable approach for scientific studies but certainly inappropriate for an end user, the second group is very diverse and includes over-the-air (OTA) electric power delivery [2,6,8,11], as well as solar [7] and electrochemical cells [12,13].…”

“…For a glucose sensing application, it would be important to mention several recent reports in the literature showing that the tear glucose concentration is quite adequately correlated (that is, real-time amounts) to blood glucose levels [5,26,27]. Given that the overall dynamic volume of basal tears is in the 10-ml range and that no known methodology can ensure that the entire volume is reliably and repeatedly exposed to the appropriate FC modules, glucose is an unlikely on-lens energy source, if conventional (bio) FCs are to be employed.…”