Editors' ChoiceDiabetes

Needles no more

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Science Translational Medicine  25 Apr 2018:
Vol. 10, Issue 438, eaat4481
DOI: 10.1126/scitranslmed.aat4481

Abstract

A needle-free graphene-based biosensor monitors blood glucose levels in real time.

Frequent monitoring of blood glucose levels is crucial for preventing diabetic complications. In practice, however, patients often fail to follow this recommendation due to the pain and discomfort from the invasive finger-stick procedures. There is a real need for an accurate, noninvasive, real-time glucose monitoring system to improve patient care, and also to complete the feedback loop for automated therapies. Yet, existing noninvasive strategies either involve high variability in the detected glucose levels or still require finger-stick calibrations.

Here, Lipani et al. developed a noninvasive, continuous glucose monitoring system to overcome these issues. The centerpiece of the system is a miniaturized thin-film pixel array of electrodes that consists of a nanoparticle-enhanced, graphene-based glucose sensor. Upon application onto the skin, a small current is applied on the electrodes to drive interstitial fluids (termed electro-osmosis) from single hair follicles into a glucose-oxidase loaded gel reservoir, which is sandwiched between the skin and electrodes. The glucose concentration is then measured based on the electrochemical current generated on the working electrodes.

Using an ex vivo porcine skin model, the authors first confirmed the operational characteristics of an individual sensor pixel at the single hair follicle level, with “quantum” detection current corresponding to single follicles. With that, they designed a pixel array with reduced operational volume and time as compared with the single pixel device, which not only provide equal or better measuring characteristics but also robustness against interfering species in real-life conditions, and minimal differences in pixels within an array and between arrays. Importantly, the researchers further tested their prototype on two healthy human volunteers, benchmarking the real-time measured glucose levels against a commercial glucose meter over a 6-hour period. The interstitial glucose profile measured with their system closely follows the blood glucose profile, with an expected 15-min delay. Although further studies are needed with the full clinical range of glucose levels in diabetes, more challenging environmental factors, and longer measurement durations, the results shown here have demonstrated great potential of the system for calibration-free noninvasive glucose monitoring in diabetic care.

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