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Proceedings Paper

Development, assembly, and validation of an SMA-actuated two-joint nozzle and six-channel power supply for use in a smart inhaler system
Author(s): Stephen J. Furst; Rohan Hangekar; Stefan Seelecke
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Paper Abstract

The Smart Inhaler design concept recently developed at NC State University has the potential to target the delivery of inhaled aerosol medication to specified locations within the lung system. This targeted delivery could help patients with pulmonary ailments by reducing the exposure of healthy lung tissue to potentially harmful medications. However, controlled delivery can only be accomplished if medication is injected at a precise location in an inhaled stream of properly conditioned laminar flow. In particular, the medication must be injected into the inhaled flow using a small nozzle that can be positioned without disturbing the flow. This paper outlines the procedure used to assemble and control a key component of the smart inhaler: a shape memory alloy (SMA) based dual-joint flexible nozzle that exploits the sensing and actuating capabilities of thermally activated SMA wires. A novel 6-channel power-supply is used to control input power and measure the resistance across the SMA. Since a practical fabrication process may result in SMA wires with different contact resistances, the power supply employs an initialization procedure to self-calibrate and provide normalized power distribution 6 SMA wires simultaneously. Furthermore, a robust control scheme is used to ensure that a constant current is provided to the wires. In validation tests, a LabVIEW-based video positioning system was used to measure the deflection of the nozzle tip and joint rotation. Results show that the carefully controlled assembly of a stream-lined nozzle can produce a practical smart structure, and joint rotation is predictable and repeatable when power input is also controlled. Future work will assess the use of the SMA-resistance measurement as position feedback and PID position control power as a measurement of the convective cooling that results from the moving airflow.

Paper Details

Date Published: 12 April 2010
PDF: 13 pages
Proc. SPIE 7643, Active and Passive Smart Structures and Integrated Systems 2010, 76430J (12 April 2010); doi: 10.1117/12.853399
Show Author Affiliations
Stephen J. Furst, North Carolina State Univ. (United States)
Rohan Hangekar, North Carolina State Univ. (United States)
Stefan Seelecke, North Carolina State Univ. (United States)

Published in SPIE Proceedings Vol. 7643:
Active and Passive Smart Structures and Integrated Systems 2010
Mehrdad N. Ghasemi-Nejhad, Editor(s)

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