Switchable, bistable microactuator systems based on stimuli-responsive polymers
The ability to purify cell mixtures by sorting or even isolating single cells from a suspension has become an essential tool in research fields such as biology, biophysics or medicine. Among the label-based methods, fluorescence- or magnetic-activated cell sorting have been established, but also label-free cell sorting based on the geometrical properties of the devices can be used . Although multiple cell sorting devices have been introduced, they currently have a predefined sorting function, which is attributed to their fabrication, and therefore lack in flexibility and adaptation to various applications and sorting parameters.
In this project we focus on novel microactuator systems made from switchable polymer materials that enable dynamically adjustable cell sorting. Thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) is a suitable polymer to create responsive microactuators . This material can switch between a swollen, high volume state and a shrunken, low volume state by a phase transition at the lower critical solution temperature (LCST). In order to achieve additional control on the stimulus, photoswitches (e.g. azobenzenes or spiropyrans) are incorporated into the polymer and lead to a shift in LCST. In this way a bistable state of the hydrogel is obtained.
The final microactuator system will consist of an array of multiple pillars in different shapes and configurations. Upon local heating of individual pillars, the sorting behaviour of the device is controlled and a variety of applications come within reach.