Figure 1

Flow monitoring in microfluidic chips using capacitance measurements and smartphone communication. (a) Concept of visualizing flow conditions using a smartphone. (b) Illustration of high-precision flow monitoring using capacitance measurements. A liquid gradually filling a microchannel or capillary pump forms a double-layer capacitance (C_dl) at the electrode interface. The effective capacitance (C_eff) is then calculated by measuring the time required to charge it to a set value (V_set) through an external charging resistor (R_c). (c) 3D rendered image of the portable device that can measure capacitances from two independent flow paths, display the results on an OLED display, and send the data to a smartphone via Bluetooth.