This paper presents a microfluidic sensing chip for the quick, low-cost measurement of blood plasma viscosity with a microliter sample volume. This chip is comprised of a magnetoelastic (ME) sensor, a planar measurement coil and a microfluidic system. The ME sensor is a wireless resonating sensor that operates through external magnetic fields. The planar coil is used to both actuate the sensor into mechanical resonance and detect the resonant frequency of the sensor. Due to the planar configuration of the measurement coil, the sensing chip can be fabricated by using a simple integration process (i.e., stacking and bonding) at a low cost. The sample volume required is 100 mu L. The sensing chip was first characterized by testing glycerol/water solutions with wide ranges of densities and viscosities. Next, to make a calibration plot correlating the sensor response with liquid viscosity, glycerol/water solutions with finely adjusted viscosities varying from 1.0 cP to 3.0 cP were tested, which covers the viscosity range of human blood plasma. Finally, the sensing chip was used to test various dilutions of human blood plasma samples. The results verify that the proposed sensing chip is capable of quickly measuring viscosity changes in blood plasma of small volume. (C) 2017 The Electrochemical Society. All rights reserved.