Modeling, design and validation of a novel microfluidic sensor for in-vitro isotonic measurement of microvessel...

The paper presents an innovative fluidic microdevice for in-vitro isotonic measurements of microvessel contraction/dilation. The proposed microdevice is based on the well-known fluid dynamic principle which correlates a geometrical change of a solid body immersed in a constant flow, with the differential pressure change induced in the flow itself. Indeed, a biochemically-induced change of microvessel diameter lead to a change of its hydraulic resistance which can be in-vitro measured by a differential pressure sensor. The novel microfluidic sensor has been modeled, designed and fabricated in order to properly implement this working principle. The fluidic scheme of the sensor consists of two pressure-sensorized chambers which are connected by a calibrated channel where the microvessel is placed. Experimental tests have been performed by using three microvessel passive simulators with different inner diameter (300, 600 and 800 microm), in order to validate the expected sensor functioning characterized by two sensitivities: the pressure drop S (PL) and the overall S 2-3 ones. Their measured values (S (PL,m)=2.132 mV/V/Pa, S (2-3,m)=0.787 mV/V/(mm3/s)/mm) confirm the validity of the proposed working principle and permit to be confident in a future application of the sensor in a clinical context.