Principles of a micro squeeze flow rheometer for the analysis of extremely small volumes of liquid

In this paper, the analysis and design of a piezoelectrically actuated micro squeeze flow rheometer (MSFR) is presented. The fabrication of a simple prototype is described and initial experiments show the validity of the theory presented. The rheometer requires small volumes of liquid of the order of 1-10 nL and extends the frequency range an order of magnitude beyond that possible using conventional cone and plate rheometry. The electrodes of the piezoelectric disc which are used to actuate the rheometer have been patterned to allow the simultaneous measurement of the induced voltage, the phase and amplitude of which is then used to calculate the storage and loss moduli of the fluid being tested.