This paper presents experimental study and numerical simulation of the electro-thermo-mechanical behavior of a
commercially available Flexinol shape memory alloy (SMA) wire . Recently, a novel driver device has been
presented , which simultaneously controls electric power and measures resistance of an SMA wire actuator. This
application of a single wire as both actuator and sensor will fully exploit the multifunctional nature of SMA materials
and minimize system complexity by avoiding extra sensors. Though the subject is not new [3-6], comprehensive
resistance data under controlled conditions for time-resolved and hysteresis-based experiments is not readily available
from the literature.
A simple experimental setup consisting of a Flexinol wire mounted in series with the tip of a compliant cantilever
beam is used to systematically study the SMA behavior. A Labview-based data acquisition system measures actuator
displacement and SMA wire stress and resistance and controls the power passed through the SMA actuator wire. The
experimental setup is carefully insulated from ambient conditions, as the thermal response of a 50-micron diameter
Flexinol wire is extremely sensitive to temperature fluctuation due to convective heat transfer.
Actuator performance is reported for a range of actuation frequencies and input power levels. The effect of varying
actuator pre-stress is reported as well. All of the experimental data is compared with simulated behavior that is derived
from a numerical model for SMA material [7-10].
This paper documents the development of a prototype smart aerosol drug inhaler system using shape memory alloy
(SMA) actuators. Unlike conventional dispersed-release inhalers, the smart inhaler system releases the aerosol drug in a
very small area within the mouth inlet. Kleinstreuer and Zhang  have found that controlled release in the mouth inlet
increases drug efficiency and allows targeting of specific sites within the lung. The methodology has been validated
numerically and experimentally using fixed-exit position inhalers. The design presented in this work, however, allows
for variation of nozzle exit position using SMA wire actuators in a combined actuator/sensor role. In contrast to other
possible mechanisms, SMA wires are lightweight, require low power, and are the least obstructive to the flow of air
through the inhaler. The dual actuator/sensor nature of the SMA wires (via resistance measurement) further simplifies
the design. Solutions and insights into several SMA actuator design challenges are presented. SMA wire actuator
characteristics such as achievable stroke and their effect on the design are highlighted. Consideration of actuator force
requirements and the capabilities of SMA wires and studied. The problems posed by the thermal characteristics of SMA
wires and innovative solutions are reported.