Low-Distortion Surface Functionalization of Polymeric Microstructures

Fabrication of Functional Microdevices in SU-8 by Multi-Photon Lithography

This review surveys advances in the fabrication of functional microdevices by multi-photon lithography (MPL) using the SU-8 material system. Microdevices created by MPL in SU-8 have been key to progress in the fields of micro-fluidics, micro-electromechanical systems (MEMS), micro-robotics, and photonics. The review discusses components, properties, and processing of SU-8 within the context of MPL. Emphasis is focused on advances within the last five years, but the discussion also includes relevant developments outside this period in MPL and the processing of SU-8. Novel methods for improving resolution of MPL using SU-8 and discussed, along with methods for functionalizing structures after fabrication.

Passive fluidic micro-sensor with all-optical readout realized using a direct laser writing technique

In this Letter, we report on design and realization of solvent-sensitive microstructures based on three-dimensional periodic lattices fabricated in a polymeric photoresist. Sensing is based on reversible size change in polymeric microstructures upon immersion in wetting and non-wetting solvents. Its readout is achieved purely optically by observing modification of a Moiré pattern formed by grating-like deformable and rigid polymeric structures. A compact micro-sensor using these principles was realized using a direct laser writing technique in the photoresist. High sensitivity and easy optical readout of the sensor were demonstrated. In the future, sensors based on similar principles may find applications in microfluidic systems, such as lab-on-a-chip.

Combination of additive and subtractive laser 3D microprocessing in hybrid glass/polymer microsystems for chemical sensing applications

We present a novel hybrid glass-polymer micromechanical sensor by combining two femtosecond laser direct writing processes: laser illumination followed by chemical etching of glass and two-photon polymerization. This incorporation of techniques demonstrates the capability of combining mechanical deformable devices made of silica with an integrated polymer structure for passive chemical sensing application. We demonstrate that such a sensor could be utilized for investigating the elastic properties of polymeric microstructures fabricated via the two-photon polymerization technique. Moreover, we show that polymeric microstructure stiffness increases when immersed in organic liquids.

Microactuation and sensing using reversible deformations of laser-written polymeric structures

We investigate reversible deformations of polymeric microstructures fabricated using direct laser writing three-dimensional lithography upon immersion in various solvents. Swelling and shrinkage of sub-micrometre size features are induced by interaction with surrounding solvent and such deformations can be exploited to create larger structures whose size, shape, and other structural parameters depend on the surroundings. We describe diffractive optical elements, micro-mechanical sensors and also hybrid deformable structures, that can be used to implement micro-actuation, micro-sensing, and other functionalities highly sought for micro-optical, micro-mechanical, and micro-fluidic systems.