A MEMS viscometer for unadulterated human blood

The design and theoretical modelling of an oscillating micro-mechanical viscometer designed for the measurement of whole unadulterated human blood, is described. The proposed device utilises the dependence of the squeeze-film damping ratio on properties of the surrounding fluid to measure fluid viscosity using an oscillating plate structure. The optimum geometrical configuration for the device structure has been investigated and a methodology for defining the optimum configuration of the micro-mechanical sensor identified. This is then applied to calculate the predicted noise equivalent viscosity change NEΔηNEΔη. It was found that the device performance is limited by electronic noise within the detection circuitry rather than thermal-mechanical noise. An electronic noise limited measurement resolution of ⩽0.11%⩽0.11%, is predicted for measurement over a shear range of 1.0→1000s-1, at a measurement bandwidth of 50Hz. The linearity of response of the micro-mechanical viscometer is considered and the device is predicted to provide a linear measurement response.