Precise cell placement by pneumatic anchoring

This work presents a novel approach to trapping and placing a defined number of living cells on a microchip for biosensing and drug-screening applications. Cells are attracted from a liquid suspension by pneumatic anchoring through small orifices (3 /spl mu/m) on the chip surface, which allow for applying suction from the backside of the chip. In contrast to other cell handling techniques, pneumatic anchoring is a very mild, physical technique, which allows for permanent cell immobilization in a parallel fashion. In most cases, pressure needs only to be applied during cell placement, as they afterwards adhere to the protein-conditioned surface and remain at their position. The chip is fabricated using silicon-on-insulator (SOI) wafers by using combined front- and backside etching. Pneumatic particle handling has been studied using polymer beads and living cells suspended in physiological buffer solutions.