High-Pressure Microhydraulic Actuator

Actuation forces of 2.1 and 5.3 pounds (9.3 and 24 N) at velocities of 1 and 0.5 mm/s have been demonstrated with compact electrokinetic pumps producing 200 μL/min at 400 psi (2.8 MPa) and 100 μL/min at 1000 psi (6.9 MPa). This output compares favorably with electromechanical actuators (solenoid, piezoelectric, stepper motor) of similar size and is achieved silently and with no moving parts. Electrokinetic pump monoliths based on phase-separated porous methacrylate polymer monoliths and slurry-packed, sintered silica monoliths have been developed that can generate electrokinetic pressures of 3 psi/V (21 kPa/V) and 8 psi/V (6.9 kPa/V), respectively. Corresponding maximum power conversion efficiencies of 1% and 3% have been demonstrated in 10 mM TRIS-HCI at pH 8.5. Gas-bubble-free electrodes have been demonstrated to deliver 2 mA and seal to 1200 psi (8.3 MPa) for microhydraulic actuation.