Water-responsive programmable shape memory polymer devices

Shape memory polymers (SMPs) have a number of advantages as compared with their metal counterpart, namely shape memory alloys (SMAs), in particular for some particular medical applications. The recent finding of the influence of moisture on the glass transition temperature of polyurethane SMPs, which are typically thermo-responsive in nature, enable us to realize not only the water driven feature for shape recovery, but also the recovery following a predetermined sequence, i.e., programmed recovery. Utilizing these new features, we demonstrate a few novel applications of this SMP, which might be of the particular interest for medical devices in, for instance, minimally invasive surgery.