Electrically activated normally closed diaphragm valves

Abstract

Thermal actuation of integrated valve structures is attractive due to the relative simplicity of the actuator design, the moderate activation time possible, the relatively low total power required, and the ability to fully integrate the actuator with the flow control component. Of the many thermal actuation schemes, the use of bimetallic elements is preferred, particularly when a low cost, fully integrated structure is desired. Bimetallic structures allow both normally-open and normally-closed valves by varying the boundary conditions at the support for the actuator, which is difficult to achieve with many alternate technologies. One such valve has been designed to provide fully proportional control of flows in the range of 0-150 cc min-1 at input pressures between 1 and 50 PSIG. The valves are batch fabricated using silicon micromachining techniques. By combining these valves with pressure or flow sensing elements, closed loop pressure or flow control is easily accomplished.

Microvalve for Fuel Cells and Miniature Gas Chromatographic System

“…The schematic of the thermally actuated microvalve developed by Jerman [58,59] is shown in Figure 2 A micromachined bimorph pressure-driven actuated valve developed by Trah et al [60] is shown in Figure 2 Lisec et al [61] developed a normally closed design based on buckling of the support beams attached to a mesa. A schematic diagram of the valve is given in Figure 2.4.24.…”

Design, fabrication and characterization of a novel gas microvalve using micro- and fine-machining

“…Many efforts have been made to develop various microvalves to meet different requirements for specific applications [2][3][4][5][6][7][8][9]. Though the configurations of these valves could be different (open or closed valve), the structures are very similar.…”

“…Therefore, the actuator's stroke and the forces delivered are limited. Table 1 gives an overview of earlier demonstrated microvalve [3][4][5][6][7][8][9]. Some of these valves meet most of the requirements, such as high inlet pressure, low leakage and process gas isolation but have relatively low flow rates [2,3,6,7].…”

Micro-jet Pump for Micro-fluidic Systems

“…Moving parts, in most cases membranes fabricated of silicon or additionally required active or passive valves, may result in short lifetime and low reliability. Displacement pumps with bimetallic [2], electrostatic [3,4], thermo-pneumatic [5,6], piezoelectric [7,8] and other drivers [9] have been reported. The properties of those systems regarding long term stability are still not known.…”