As the fossil fuels are depleting with time, the research work in the biofuels domain is rapidly growing. The blends of biofuel can be used as automobile fuel and the existing methods to detect the blending ratio have heavy one-time test cost, need controlled environment and require experienced operators. It is well observed that fuel mixture affects lubricating properties of the fuel and thereby the engine performance. As lubricating properties are related to physical properties, developing a sensor, based on this, can provide a reliable and effective solution to detect and monitor fuel blending. This work describes the computational and the comparative experimental analysis of a microfluidic-device which performs blending studies by analyzing the interface position of the fluid occupancy in a micro-channel and its variations. The device was fabricated in acrylic using a well-established micro-fabrication technique, and is re-usable, re-calibrated and can be integrated with the existing microcontrollers of automobiles. The viscosity of the various bio-diesel blends can be used to indicate the fraction of bio-diesel in the fuel sample based on the best fit curve of the percentage of channel fraction occupied by the samples. The interface shift is because of the greater occupancy rate of a higher viscous sample in the channel. The best fit curve was determined based on an extensive testing of various oils including the hair oils, machine oils etc. of different densities to confirm the interface shifting phenomenon. © 2014 Elsevier Ltd. All rights reserved.