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 μm) 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.