Optofluidic microviscometer (OMV) for measuring adulteration and blending in fluids

Abstract

This thesis describes the designing, fabrication, theoretical modeling and experimental validation of a 3D printed lab-on-chip microfluidic device which measures adulteration by analyzing the variations in dynamic viscosity of a fluid in a palm-sized variant without the need of an experienced operator. The working principle in this device is viscosity dependent width capture by two immiscible fluids flowing into a rectangular microchannel at the same flow rate. The theoretical model of the device has been based on the modified Hagen-Poiseuille flow equation with emphasis on flow rate, sample volume and viscosity as major parameters. The dynamic viscosity of various samples have been tested w.r.t a reference solution and the test results have been verified using a standard rheometer. The tests were conducted for three types of sample groups. The first group comprised of several blending ratios of diesel with biodiesel. The second group was a sample galore of various commonly mixed adulterants (of different ratios) in milk. The third and final group consisted of samples formed by a mixture of three conventional fuels namely petrol, diesel and kerosene. The design and fabrication of the device using the conventional micromachining and the advanced 3D printing technology has been discussed in detail. This optical microviscometer has many advantages over other devices like simple design, quick 3D fabrication, low cost, low sample volume, excellent insulation, transparency, durability and accuracy. The simple and versatile device design offers the advantage of being compatible for many other applications like food adulteration, haemoglobin detection, PT-INR measurement, etc.