Shrinkage Analysis of Carbon Micro Structures Derived from SU-8 Photoresist

Abstract

We present preliminary results for the analysis of shrinkage of 3D carbon posts obtained by the pyrolysis of SU-8 precursor structures, in a technique known as Carbon MEMS. Though the shrinkage in the carbon structures is highly reproducible, there is a strong dependence of this shrinkage on the initial dimensions of the SU-8 pillars. Our hypothesis is that the shrinkage depends upon the area available for degassing during carbonization. In this work, this idea is used to analyze shrinkage in cylindrical pillars. The results obtained are studied based on the ratio of lateral and top surface area available for degassing and reinforce the hypothesis about the dependence on surface area.

3D‐Printed Carbon Electrodes for Neurotransmitter Detection

“…The small standard deviations indicate high reproducibility of fabrication. The shrinkage factor was 0.61±0.02 ( n =5) for spheres and 0.62±0.04 ( n =4) for cones, comparable to previously reported values for SU‐8 . Smaller spherical microelectrodes, printed on 10 μm platinum wires, were also fabricated to demonstrate the tunable size (Figure e,f).…”

“…The shrinkage factor was 0.61 ± 0.02 (n=5) for spheres and 0.62 ± 0.04 (n=4) for cones, comparable to previously reported values for SU-8. [22] Smaller spherical microelectrodes, printed on 10 µm platinum wires, were also fabricated to prove the tunable size (Figure 2e-f). The designed diameter is 100 μm, the structure shrinks to 90 μm after printing, and after annealing the diameter is about 30 μm.…”

Fabrication challenges and perspectives on the use of carbon‐electrode dielectrophoresis in sample preparation

“…Current DEP devices feature an electrode height of around 100 µm with an aspect ratio between 2 and 4. The shrinkage during carbonisation is near isometric and depends on the ratio between surface area and volume of the polymer precursor [39]. A structure featuring a high ratio shrinks more than one with small ratios since there is more area available for material evaporation during carbonisation.…”

3D‐Printed Carbon Electrodes for Neurotransmitter Detection

“…The printing time was about 7min for the sphere and 17 min for the cone,and up to 20 electrodes could be printed per batch. [22] Smaller spherical microelectrodes,p rinted on 10 mmp latinum wires, were also fabricated to demonstrate the tunable size (Figure 2e,f). Thes hrinkage is due to the residual stresses when covalent bonds are formed [20] and could be predicted and compensated for in the future.…”

“…Theshrinkage factor was 0.61 AE 0.02 (n = 5) for spheres and 0.62 AE 0.04 (n = 4) for cones, comparable to previously reported values for SU-8. [22] Smaller spherical microelectrodes,p rinted on 10 mmp latinum wires, were also fabricated to demonstrate the tunable size ( Figure 2e,f). Thed esigned diameter is 100 mm, the structure shrinks to 90 mma fter printing, and after annealing the diameter is about 30 mm.…”