Shape Memory Alloy Actuation of a Metered-Dose Inhaler

Respiratory diseases such as asthma or chronic obstructive pulmonary disorder (COPD) affect millions of people around the world. The most common treatment approach is to take an inhaled corticosteroid as needed with a dry-powder inhaler or a metered-dose inhaler. Unfortunately, rates of inhaler mishandling and misuse are staggeringly high and as a result, the majority of those suffering from asthma and COPD are not receiving proper treatment. There are a myriad of ways inhalers are mishandled and misused, but one significant challenge results from the timing miscoordination of the medicine dispersion and inhalation breath. To address this, the current study successfully demonstrates the feasibility of automating the timing of the medicine dispersion by the addition of a Shape Memory Alloy (SMA) actuator and a differential pressure sensor into the casing of a traditional metered-dose inhaler. To meet actuation requirements and reliably depress the inhaler cartridge, the SMA wire was routed around a set of miniature bearings within the casing of the inhaler. By demonstrating that a metered-dose inhaler may be actuated by SMA without a significant increase of its weight or size, this study provides a practical technological approach to reducing the improper treatment of asthma and COPD due to inhaler misuse.