ROBUST DESIGN OF GAS AND LIQUID MICROPUMPS

Due to the small stroke of micro actuators, the compression ratio of m icropumps is frequently small. This means that serious constraints exi st for most micropump designs concerning self-priming capability and b ubble tolerance. To access this problem in this study, criteria for th e minimum compression ratio of a micropump are derived depending on th e medium transported. It turns out that under real operation and handl ing conditions(outgassing, incomplete priming) design rules applicable for gas pumps also have to be used for liquid pumps. Next, if the liq uid pump is to be able to prime itself, a critical pressure has to be achieved, which leads to a further increase of the necessary compressi on ratio. To determine this critical pressure, the surface and interfa cial energies of the liquid have to be taken into account. (C) 1998 El sevier Science S.A. All rights reserved.