Design and microfabrication of a high-aspect-ratio PDMS microbeam array for parallel nanonewton force measurement and protein printing

Cell and protein mechanics has applications ranging from cellular development to tissue engineering. Techniques such as magnetic tweezers, optic tweezers and atomic force microscopy have been used to measure cell deformation forces of the order of piconewtons to nanonewtons. In this study, an array of polymeric polydimethylsiloxane (PDMS) microbeams with diameters of 10-40 mu m and lengths of 118 mu m was fabricated from Sylgard (R) with curing agent concentrations ranging from 5% to 20%. The resulting spring constants were 100-300 nN mu m(-1). The elastic modulus of PDMS was determined experimentally at different curing agent concentrations and found to be 346 kPa to 704 kPa in a millimeter-scale array and similar to 1 MPa in a microbeam array. Additionally, the microbeam array was used to print laminin for the purpose of cell adhesion. Linear and nonlinear finite element analyses are presented and compared to the closed-from solution. The highly compliant, transparent, biocompatible PDMS may offer a method for more rapid throughput in cell and protein mechanics force measurement experiments with sensitivities necessary for highly compliant structures such as axons.