Abstract
Currently available point-of-care systems for body fluid collection exhibit poor integration with sensors. Herein, the design of a disposable device for interstitial fluid (ISF) extraction as well as glucose, lactate, and potassium ion (K(+)) monitoring is reported on. It is minimally invasive and appropriate for single use, minimizing the risk of infection to the user. This microscale device contains a 3D-printed cap-like structure with a four-by-four microneedle (MN) array, bioreceptor-modified carbon fiber (CF)-sensing surface, and negative pressure convection technology. These features are incorporated within a compact, self-contained, and manually operated microscale device, which is capable of withdrawing ≈3.0 μL of ISF from the skin. MN arrays applied with an upward driving force may increase the ISF flow rate. Moreover, functionalized CF working electrodes (WE(1), WE(2), WE(3)) are shown to selectively detect lactate, glucose, and K(+) with high sensitivities of 0.258, 0.549, and 0.657 μA μm (-1) cm(-2) and low detection limits of 0.01, 0.080, 0.05 μm, respectively. Ex vivo testing on porcine skin is used to detect the ISF levels of the biomarkers. The microscale device can be a replacement for current point-of-care diagnostic approaches.