This paper reports the development of a novel electronic micro-viscometer capable of measuring viscosity of different Newtonian fluids using less than 100 µl which is highly sensitive, operates on the principle of capacitance change of a microfluidic channel where fluid flows without any external force. A novel electrical approach is developed to study the Newtonian fluids flow characteristics within the microfluidic channel. Special attention is devoted to mathematical modeling, device fabrication and its electrical characterization with diesel/biodiesel and its different compositions (dynamic viscosity ranges 0.1–10 cP) to study the Newtonian fluids flow characteristics and viscosity. Micro-viscometer is realized using standard silicon process techniques; the device has a closed micro-channel with a reservoir on one side and a sink on the other. The channel wall is coated with SiO2, allowing passive pumping of various fluids due to its hydrophilic behavior. The devices are analyzed using 3D optical imaging and electrical characterization in the presence of diesel/bio-diesel and its different compositions. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.