A testing device uses a selectively deformable substrate to capture and retain spherical beads for genetic experimentation. A method of fabricating the device is described in which a silicon substrate can be coated with a photosensitive, bio-compatible polymer for photolithographic patterning using a single mask exposure. The polymer is patterned with a matrix of wells, each well capable of expansion to accept placement of a bead in the well, and contraction to secure the bead in the well. The polymer can exhibit piezoelectric properties that cause it to respond mechanically to a selected electrical excitation.