Pipette Based Viscometer with Pressure Sensor Element

This paper reports a simple viscometer, whose principle utilizes the relationship between liquid viscosity and the suction speed in a tube. The proposed viscometer is composed of an air chamber and a glass tube. A steel ball is attached to the silicone membrane of the chamber and an electromagnetic magnet is used to provide the volume change. A MEMS pressure sensor element is attached to the chamber to measure its pressure change. When a step-response volume change is applied, the chamber pressure decreases so that the liquid sticking to the tube gradually ascends at a speed depending to the viscosity. Thus, the viscosity can be calculated by measuring the gradient of the pressure change. The proposed method can be applied to micropipettes so that viscosity is easily measured with a simple device.