| Popis: |
Conventional technologies that are deployed in contemporary irrigation systems need improvement, especially for precise metering of water to individual plants. In this study, a novel thermally-actuated hybrid microvalve was designed, fabricated, assembled, and tested using soft lithography-based approaches to develop microfluidic platforms which enable precise delivery of water volumes to individual plant for precision agriculture application (other applications include hydroponics and deep-space missions). The modified design integrates the “normally open and closed” hybrid configurations of Tesla Valves with a thermo-pneumatic actuator microfabricated in-situ - that modulates the diodicity of the microvalve apparatus in the microfluidic chip. Here, diodicity (Di) is defined as the ratio of flow rate in the forward direction to that of the reverse direction (for a constant value of pressure drop that is imposed on a microvalve device). The results from the study successfully demonstrated the operation of an array of Tesla Valves that are normally open in forward direction and marginally closed in reverse direction at room temperature (i.e., with Di > 1, the flow resistance values were different when the inlet and outlet ports were swapped). When the microfluidic chip was heated (at steady state conditions with a nominal temperature of ∼30°C), the diodicity virtually vanished (i.e., Di ≈ 1) resulting in both reverse and forward directions being normally open (or having the same flow resistance - irrespective of the flow direction). |
