A shape memory alloy microvalve with flow sensing

Matthew E. Piccini, Bruce C. Towe

Research output: Contribution to journalArticle

32 Citations (Scopus)

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.

Original languageEnglish (US)
Pages (from-to)344-349
Number of pages6
JournalSensors and Actuators, A: Physical
Volume128
Issue number2
DOIs
StatePublished - Apr 19 2006

Fingerprint

shape memory alloys
Tubing
Shape memory effect
Silicones
Ruby
Wire
Thermocouples
silicones
ruby
wire
thermocouples
Joule heating
Channel flow
balls
nitinol alloys
Contacts (fluid mechanics)
Derivatives
channel flow
Temperature
plugs

Keywords

  • Flow sensor
  • Microfluidic
  • Microvalve
  • Shape memory alloy

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Mechanical Engineering
  • Instrumentation

Cite this

A shape memory alloy microvalve with flow sensing. / Piccini, Matthew E.; Towe, Bruce C.

In: Sensors and Actuators, A: Physical, Vol. 128, No. 2, 19.04.2006, p. 344-349.

Research output: Contribution to journalArticle

Piccini, Matthew E. ; Towe, Bruce C. / A shape memory alloy microvalve with flow sensing. In: Sensors and Actuators, A: Physical. 2006 ; Vol. 128, No. 2. pp. 344-349.
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