Figure 1.

Schematic side and top views of our device. We create the device by sealing a PDMS mold (containing two reservoirs connected by a pore) to a glass coverslip, and then filling it with solution. Pressure is used to drive the particles through the pore. The electrical current across the pore is measured at constant applied voltage by using a four-point technique, where the inner (outer) electrodes control the voltage (current). Incorporated into the top view is an optical image of an actual sealed device containing a 7-μm-long, 1-μm-wide pore.