Nicholas T. Kattamis

Thick film laser induced forward transfer for deposition of thermally and mechanically sensitive materials

Laser forward transfer processes incorporating thin absorbing films can be used to deposit robust organic and inorganic materials but the deposition of more delicate materials has remained elusive due to contamination and stress induced during the transfer process. Here, we present the approach to high resolution patterning of sensitive materials by incorporating a thick film polymer absorbing layer that is able to dissipate shock energy through mechanical deformation. Multiple mechanisms for transfer as a function of incident laser energy are observed and we show viable and contamination-free deposition of living mammalian embryonic stem cells.

Time-resolved study of polyimide absorption layers for blister-actuated laser-induced forward transfer

Blister-actuated laser-induced forward transfer (BA-LIFT) is a versatile, direct-write process capable of printing high-resolution patterns from a variety of sensitive donor materials without damage to their functionality. In this work, we use time-resolved imaging to study the laser-induced formation of blisters on polyimide films in order to understand and optimize their role in BA-LIFT. We find that the initial blister expansion occurs very rapidly (<100 ns), followed by a brief oscillation (100–500 ns), and then a longer time contraction to steady-state dimensions (0.5–50 μs). This behavior is explained by kinetic and thermal effects that occur during the process. We further probe the influence of polyimide thickness, laser beam diameter, and laser fluence on blister formation characteristics. Results indicate that the presence of a thin layer of donor material on the polyimide surface does not have a significant effect on the size and shape of the blisters which form.

Laser direct write printing of sensitive and robust light emitting organic molecules

We examine the effects of three laser direct-write (LDW) printing techniques on 9-anthracenemethanol and tris(8-hydroxyquinoline)aluminum (Alq3) organic luminophores in order to link the differences in transfer mechanism to the resulting material properties. Degradation can occur where laser light and elevated temperatures are transferred to the molecules, such as those printed via matrix-assisted or thin metal absorptive layer LDW. In contrast, thick film polyimide absorbing layer techniques eliminate damage in these sensitive materials by shielding them from excessive heat and laser illumination.