A micromachined elastomeric tip array for contact printing with variable dot size and density

We report a flexible and versatile microcontact printing process using a micromachined elastomeric PDMS (poly-dimethylsiloxane) stamp with two-dimensional arrays of pyramidal tips. The PDMS stamp was molded from a bulk-etched single-crystalline silicon master. By changing the contact pressure, arrayed dot patterns with different dot sizes (from submicron to a few microns) were obtained controllably with one single PDMS stamp. Variable density of dot patterns was also achieved in a 'step-print' manner by conducting multiple printing on a transitional stage. This technique is expected to be useful in many nano- and biotechnology applications, including single cell and neuron studies.