A Colorimetric Sensor for Point-of-Care Detection of Pancreatic Lipase Using an Oil-in-Water <i>μ</i>-Emulsion Substrate

Pancreatic illnesses and injuries can lead to a wide array of potentially life-threatening diseases. Therefore, it is crucial to regularly assess pancreatic health, which can be done by monitoring the levels of pancreatic lipase in blood serum. In this work, we report the development of a microfluidic colorimetric sensor to detect the concentration of pancreatic lipase in human blood serum. The sensor is composed of a microcuvette assembled within a small, handheld, portable 3D-printed box. The sensor substrate is an oil-in-water microemulsion stabilized by alcohol, that enables the enzyme present in the water phase (e.g. serum) to come in contact with the fat (e.g. olive oil) and hydrolyze the same to release fatty acids and protons into an aqueous medium. The variations in the pH of the aqueous medium have been followed by the change of color of a pH indicator. This color change is measured by illuminating the microcuvette sensor with a light-emitting diode from one side and measuring the change in the intensity of transmitted light with the help of a photoresistor from the other side. The resistance across the photoresistor shows a linear variation with the concentration of pancreatic lipase. The device is calibrated against a series of analytes with known concentrations of pancreatic lipase. The low-cost, portable solution provided can serve as point-of-care diagnostic kit to assess pancreatic health at patients’ site.