Fabrication of three-dimensional microstructures based on singled-layered SU-8 for lab-on-chip applications

This paper introduces a novel 3D manufacturing approach to the rapid processing of microfluidic components such as embedded channels and microvalves, using a scanning laser system. Compared to existing manufacturing techniques, our direct UV laser writing method greatly simplifies fabrication processes, potentially reducing the design-to-fabrication time to a few hours, which is extremely beneficial during the product development stages. The initial process validation has been presented by using SU-8 material. With the fine-tuning of the laser processing parameters, the depth of SU-8 polymerization can be controlled. This paper also describes the underlying theory and method to determine the Young's modulus of the exposed SU-8 material by using a laser acoustic microscopy system. The laser-based ultrasonic technique offers a non-contact, nondestructive means of evaluation and materials characterization. More importantly, it allows for local inspection of material properties. The results presented in this paper potentially could serve as the first crucial step towards the rapid manufacturing of microdevices for lab-on-chip applications.