Shape memory alloy based test strip ejection mechanism

摘要

In the following a concept is shown using a shape memory alloy (SMA) element, e.g. a SMA wire, to eject a test strip. The small displacement of the SMA wire caused by the temperature change is increased by a lever arm. The relocation of the wire into its former state is performed by an inverse movement when the user is inserting the next test strip. Figure 1 shows an implementation of the ejection mechanism with linear displaceable mounting block (1) where the SMA wire crimps are fixed. The SMA wire (2) is placed around a lever arm (3). In order to achieve a compact actuator, a large conversion ratio of the lever arm, e.g. 1 by 7 is suggested. The long side of the lever arm may be designed with a cylindrical shaped pin. This may connect with a slot in a slider to move the test strip.