Much research has been ongoing to develop diagnostic biochips that can be used to efficiently analyze least amount of sample in a short period of time. the available devices do not have many integrated sensors, and have issues like cross contamination, unstable temperature of the substrate/reagents, non re-usability of the microchips etc. the present invention relates to a lab-on-a-chip (loc) device and provides an electrolyte insulator semiconductor (eis) based microfluidic immunosensor, which measures the changes in surface potential between the electrolyte (desired analyte) and the sensing insulator by a shift in capacitance voltage (cv) curves. this shift is a direct representation of sensitivity of the device from which quantification of a particular disease marker (present in the sample) can be obtained. this device provides a reliable detection of different biomarkers, specifically cancer, and for other diseases.