Multiphoton Lithography

Multiphoton Lithography also called Two Photon Polymerization is a Additive Manufacturing tool with an unique resolution down in the submicron range. In the very focal point of a femto second pulsed laser the so called two photon initiator is excited and is able to undergo classical photochemistry such as radical formation. Classical photoinitiators are not suitable due to the low two photon absorption cross-section. Therefore we have developed in the last decade a series of new multiphoton initiators. Triple bond containg derivatives are less prone to cis-trans deactivation pathways usually found in double bond containg derivatives. [1,2] Furthermore, several other aromatic ketone based photoinitiators were introduced which have a significantly improved two photon absorption cross-section. [3,4] Especially the exact and comparable measurement of this value is challenging. [5] As the evaluation of the printed structures is quite challenging due to the small voxel size FTIR spectroscopy and nanoindentation measurements were established. [6,7] Possible applications for this Additive Manufacturing tool are manyfold such as in tissue engineering or the electronic industry [8,9]

[1] C. Heller, N.U Pucher, B. Seidl, K. Kalinyaprak-Icten, G. Ullrich, L. Kuna, V. Satzinger, V. Schmidt, H. Lichtenegger, J. Stampfl, R. Liska: "One- and two-photon activity of cross-conjugated photoinitiators with bathochromic shift"; Journal of Polymer Science Part A: Polymer Chemistry, 45 (2007), S. 3280 - 3291.

[2] N.U Pucher, A. Rosspeintner, V. Satzinger, V. Schmidt, G. Gescheidt, J. Stampfl, R. Liska: "Structure-Activity Relationship in D-π-A-π-D-Based Photoinitiators for the Two-Photon-Induced Photopolymerization Process"; Macromolecules, 42 (2009), S. 6519 - 6528.

[3] Z. Li, M. Siklos, N.U Pucher, K. Cicha, A. Ajami, W. Husinsky, A. Rosspeintner, E. Vauthey, G. Gscheidt, J. Stampfl, R. Liska: "Synthesis and Structure-Activity Relationship of Several Aromatic Ketone-Based Two-Photon Initiators"; Journal of Polymer Science Part A: Polymer Chemistry, 49 (2011), S. 3688 - 3699.

[4] Z. Li, N.U Pucher, K. Cicha, J. Torgersen, S. Ligon, A. Ajami, W. Husinsky, A. Rosspeintner, E. Vauthey, S. Naumov, T. Scherzer, J. Stampfl, R. Liska: "Straightforward Synthesis and Structure-Activity Relationship of Highly Efficient Initiators for Two-Photon Polymerization"; Macromolecules, 46 (2013), 2; S. 352 - 361.

[5] A. Ajami, P. Gruber, M. Tromayer, W. Husinsky, J. Stampfl, R. Liska, A. Ovsianikov: "Evidence of concentration dependence of the two-photon absorption cross section: Determining the ``true´´ cross section value"; Optical Materials, 47 (2015), S. 524 - 529.

[6] K. Cicha, Z. Li, K. Stadlmann, A. Ovsianikov, R. Markut-Kohl, R. Liska, J. Stampfl: "Evaluation of 3D structures fabricated with two-photon-photopolymerization by using FTIR spectroscopy"; Journal of Applied Physics, 110 (2011), 064911; S. 1 - 5.

[7] K. Cicha, T. Koch, J. Torgersen, L. Zhiquan, R. Liska, J. Stampfl: "Young´s modulus measurement of two-photon polymerized microcantilevers by using nanoindentation equipment"; Journal of Applied Physics, 112 (2012), 094906.

[8] J. Kumpfmüller, K. Stadlmann, V. Satzinger, L. Zhiquan, J. Stampfl, R. Liska: "Two-photon-induced Microfabrication of Flexible Optical Waveguides"; Journal of Laser Micro Nanoengineering, 6 (2011), 3; S. 195 - 198.

[9] J. Kupfmüller, Z. Li, V. Satzinger, J. Stampfl, R. Liska: "Two-photon-induced thiol-ene polymerization as a fabrication tool for flexible optical waveguides"; Designed Monomers and Polymers, (2013), S. 1 - 11.