Fig. 4: Illustration of glucose detection by the pH-responsive superwetting surface.

a Schematic representation of glucose detection based on the gluconic acid released from the GOx-catalyzed reaction. The surface could be reused after washing and drying. b Sensitivity test with different concentrations of glucose (1, 10, 100, 200, 300, 400, 500, 600, 700, 800 nM and 1, 10, 50, and 100 µM, 500 µM and 1 mM). c Linear relationship between the CA and glucose concentrations ranging from 1 nM to 800 nM. d Wetting states of droplets with different concentrations of glucose within the linear range. e The theoretical and experimental CA in the presence of different glucose concentrations ranging from 1 nM to 800 nM. The theoretical CA was obtained from the pH-responsive curve. f Relationship between the change in the CA (∆CA = | CA − CA₀ |, where CA and CA₀ are the CAs of the experimental group and the blank control, respectively) and interfering agents (fructose, mannose, arabinose, galactose, xylose and glucose). The interfering substances were tested at 0.5 mM with 10 U mL⁻¹ GOx at 37 °C for 60 min of incubation. The initial pH was 6. The volume of the test droplet was 2 µL. Error bars indicate the standard deviation of three replicates