On-chip microfabrication of thermally controllable PNIPAAm microvalves by using optical maskless stereolithography

A growing trend of lab-on-a-chip (LOC) technologies is to achieve large-scale integration of components and functionalities. In this paper, we present an optical in-situ microfabrication technology, i.e. optical maskless stereolithography, for on-chip component fabrication and integration. It is demonstrated that poly(N-isopropylacrylamide) (PNIPAAm) can be rapidly patterned into high-resolution 2D/3D microstructures and in-channel PNIPAAm microvalves can be adaptively fabricated on a microfluidic chip by using the UV light based optical maskless exposure technology. The PNIPAAm microvalve can be repeatedly switched off and on by tuning its temperature between 20 and 37 degrees C, respectively. Such an in-situ microfabrication approach is promising in the development of multifunctional microfluidic chips integrated with micro-sensors and actuators. (C) 2016 Elsevier B.V. All rights reserved.