Investigation of Transient Micro Diaphragm Pump Dynamics

A micro diaphragm pump is one of the micro dosing system used in various microfluidic applications like drug delivery systems, chemical and biological analysis and microelectronics cooling systems. Fraunhofer EMFT has designed a micro-diaphragm pump, which is capable of transporting micro and precise volumes of liquid accurately, which makes them a potential instrument in research and development. A high voltage piezoceramic actuator when glued on to the diaphragm, it allows a fast mechanical response time of few microseconds, controllability, reliability and resolution up to sub-nanometer range. These days much of the research is focused on further miniaturization, cost reduction, accurate transportation of micro and precise volume of liquid, improving mechanical response time and increasing the stroke volume of the micro-pump. To achieve this, investigation of the dynamics of the piezoelectric actuator and its effects on the operation of the micro-pump was carried out in this work. An investigation of the dynamics of axisymmetric unimorph piezoelectric actuators includes changing of the material, geometrical parameters and actuation frequency. Using Classic Laminate Plate Theory, a closed-form expressions are derived for the transverse and radial displacements under pressure and voltage loads for two types of unimorph piezoelectric actuators. Using analytical and numerical methods, the effects of geometrical and material parameter variations on the actuators performance has been investigated. These geometrical and material parameters include the dimensions, mechanical properties and type of the material of the piezoceramic and membrane, respectively. The analytical results are then compared with the non-linear FEM simulation using ANSYS workbench. The scope of the analytical solution is validated using experimental measurements.