Thermally Actuated Mechanical Valves

Thermal mechanical valves Thermally actuated mechanical valves Thermally driven mechanical valves... 

Fluid-filled bulbs dehver enough power to drive controller mechanisms and even directly actuate control valves. These devices are characterized by large thermal capacity, which sometimes leads to slow response, particularly when they are enclosed in a thermal well for process measurements. Filled-system thermometers are used extensively in industrial processes for a number of reasons. The simplicity... 

Microfluidic Control Sequential and combinatorial delivery of signals to cells or tissue in microfluidic devices can be accomplished by using built-in control systems. Several microfluidic tools including valves, pumps, mixers, fluidic oscillators, fluidic diodes, etc. have been developed to accomplish fluidic control in these devices. These components can either be passive or active. Examples of passive elements include one-way valves (flap, ball) and hydrophobic patohes which take advantage of the interactiOTi between the chemical surface properties of the substrate and Uquid. Active elements, on the other hand, typically require some type of actuation mechanism. Several mechanisms for force transduction in microfluidic devices include mechanical, thermal, electrical, magnetic, and chemical actuation systems as well as the use of biological transducers. There has been a significant amount of work in this area that has been presented in a review by Erickson and Li [5]. 

ACTUATOR - The portion of a regulating valve, which converts mechanical, fluid, thermal, or electrical energy into mechanical motion to open or close the valve seats or other such devices. 

Microfluidic valves are essential for flow control of sample and reagents on a microfluidic CD. There are two categories of valves, namely passive valves, and active valves. Passive valves have no moving parts and work on the principle of the capillary effect [6]. Active valves on the other hand require moving parts such as a membrane or plunger that requires external mechanical, pneumatic, electric or thermal force for actuation. 

Microfluidic pumps, switches and valves are used to manipulate fluid flow in microchannels (flow regulation, switching, sealing) [124, 125]. The fluid displacement inside chips can also be actuated with stimuli-responsive hydrogels [126, 127]. Mechanical means of flow control are also possible. For example, a pneumatically actuated elastomeric switch works by applying external pressure across the contact area of two crossing channels situated in two different layers [13]. Thermally formed microbubbles [128] and magnetic valves [129] can also be used for flow control. 

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