Abstract
A Nitinol™ actuated silicone tubing microvalve is combined with a downstream thermocouple forming an integrated system for the control and metering of microliter volumes. The integrated device is of a normally closed design having a break pressure of more than 68.9 kPa (517 mmHg), dimensions on the order of 1 mm × 2 mm × 2 mm, inert fluid contact surfaces, and senses flow. Power pulses of 213 mW are required for 2.5 s response times. Opening of the valve is brought about by a temperature induced metallurgical transition of a short piece of nitinol wire with a diameter of 75 μm. The force generated by the transition is harnessed in order to stretch microbore silicone tubing away from a luminal plug (synthetic ruby ball), thus forming flow channels. Actuation is performed using a pulsed paradigm with a distinctive on and off period enabling flow sensing capabilities. The integrated thermal principle flow sensor operates by sensing the peak temperature derivative of a transient thermal pulse in the flow stream imparted by joule heating of the nitinol wire when actuated. It was found that this flow sensing scheme proved to be a reliable method of detecting valve performance changes over time. The system is constructed using readily available commercial components including microbore silicone tubing, nitinol shape memory alloy (SMA) wire, a miniature synthetic ruby ball, and a thermocouple.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
