Comparison of the Technical Capabilities of Traditional Glass Surface Micromachining/Chip-on-Board and 3D Printing-based Microfabrication Technologies Utilizing a Microelectrode Array (MEA) as a Platform Device
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1
University of Central Florida, United States
Novelty/Progress Claims: We developed a benchtop, additive manufacturing based Microelectrode Array (MEA) and compared the technology to traditional cleanroom-based, glass surface micromachining/chip-on-board MEAs and found out that our 3D printing-based process compares very favorably in terms of design to device while representing a dramatic reduction in cost, timeline for fabrication, reduction in the number of steps and the need for sophisticated equipment.
Background/State of the Art: MEAs are electrochemical, microscale biosensors that have made significant contributions to further the understanding of several ‘diseases in a dish’ such as Alzheimer’s and Parkinson’s [1, 2] leading to a reduction in animal testing and hastening disease treatment. In addition to microfluidic chips, MEAs have become the most important tool toward the advancement of in vitro research in areas such as medicine, pharmacology, toxicity screening and disease modeling. Due to the cleanroom-based fabrication and the requirement of backend processes for assembly, commercial MEAs are expensive and time intensive. The disposable nature of the device and reduced resolution requirements for biological research make MEAs an ideal tool that can be addressed by new and emerging additive manufacturing based approaches.
Description of New Method: The process flow for the 3D printing-based approach is depicted in Figure 1 and compared to the glass microfabrication approach also developed in our group for a precision plating of cells application [3]. The structural base of the 3D printed device includes through vias for the microelectrodes and alignment holes for interfacing with electronics for measuring of cellular electrophysiology. A selective ink casting step defines the electrodes and an insulation layer is defined by SU-8 casting, UV-lamp exposure/bake and laser micromachining on the top-side of the chip. To create traces and contact pads on the bottom-side, evaporation of metal through a micromilled, stainless steel shadow mask is performed. Measurements of the various features listed in Table 1 on three devices of both types of MEAs were performed with an optical microscope. An AFM (Figure 2) was used to characterize the surface roughness of the 3D printing-based MEAs to compare with literature supplied roughness data for the glass MEAs.
Experimental Results: Figure 1 additionally represents 3D printed MEA images at various steps. Measurements of dimensions of microelectrodes, reference electrodes, traces, contact pads and SU-8 openings were performed. The relative deviation of the measured average from the expected design values were determined to achieve a comparison of the two technologies (Figure 2) and the underlying data of the relative deviation is represented in Table 1. The data represents less than 5% deviation from design for the 3D printing-based approach in more than the half of the categories that were measured, which is comparable to the glass approach. Additionally, a technological summary was conducted in Table 3, where the 3D printing-based approach compares favorably with the traditional approach in environment, number of process steps, time, cost and equipment/materials. Resolution of cleanroom-based approaches is superior but laser micromachining and advanced 3D printing technologies (e.g. Nanoscribe) can bridge the gap between both technologies even in this space. Lastly, comparing the surface roughness, in Table 2, the surface roughness of the 3D printed devices measures 50-150 nm and larger than the glass approach. However, when the biological applications are factored in where these devices are used as cell-based biosensors, the values obtained in the nanometer range are perfectly suitable for cells (neural, cardiac etc.) since their sizes are in micrometers. Furthermore, both fabrication techniques use SU-8 as insulation, which is self-planarizing and it reduces surface roughness issues. We believe our results are very significant for the cell-based biosensors and other communities since this technology can result in quick turnaround of ideas to a prototype that can be tested rapidly reducing cycle time between iterations and advancing the end applications such as toxicity screening and drug discovery.
References
[1] Maruyama, T., Suzuki, S., Yoshida, L., Kotani, K., & Jimbo, Y., (2013). “Delopment of a novel co-culture device of neuronal cells for construction of in vitro Alzheimer’s disease model.” Biomedical Engineering International Conference, DOI: 10.1109/BMEiCon.2013.6687710
[2] Woodard, C., Campos, B., Kuo, S.-H., Nirenberg, M., Nestor, M., et. al., (2014). “iPSC-Derived Dopamine Neurons Reveal Differences between Monozygotic Twins Discordant for Parkinson’s Disease.” Cell Reports 9, 1173-1182. DOI: 10.1016/j.celrep.2014.10.023
[3] Azim, N., Sommerhage, F., Aubin, M., Hickman, J., & Rajaraman, S., (2017). “Precision Plating of Electrogenic Cells on Microelectrodes enhanced with Nano-Porous Platinum for Cell-based Biosensing Applications.” Meeting Abstracts, MA2017-01(42), 1954-1954. Retrieved from http://ma.ecsdl.org/content/MA2017-01/42/1954.short
Keywords:
Microelectrode Array (MEA),
microfabrication,
Glass MEAs,
3D Printed MEAs,
Technological Comparisons
Conference:
MEA Meeting 2018 | 11th International Meeting on Substrate Integrated Microelectrode Arrays, Reutlingen, Germany, 4 Jul - 6 Jul, 2018.
Presentation Type:
Poster Presentation
Topic:
Microelectrode Array Technology
Citation:
Fremgen
S,
Springer
S,
Kundu
A and
Rajaraman
S
(2019). Comparison of the Technical Capabilities of Traditional Glass Surface Micromachining/Chip-on-Board and 3D Printing-based Microfabrication Technologies Utilizing a Microelectrode Array (MEA) as a Platform Device.
Conference Abstract:
MEA Meeting 2018 | 11th International Meeting on Substrate Integrated Microelectrode Arrays.
doi: 10.3389/conf.fncel.2018.38.00093
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Received:
18 Mar 2018;
Published Online:
17 Jan 2019.
*
Correspondence:
Ms. Sarah Fremgen, University of Central Florida, Orlando, Florida, 32816, United States, sarah.frem@gmail.com