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Seiti, et al.
Jet Printing as PEs technology for the development of granted to Miriam Seiti, 1SB1120N. The authors thank
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a NTE integrated device for combined electrical and Frederik Ceyssens (KU Leuven, ESAT) for Parylene-C
topographical axon guidance. Specifically, the study coating and measurement of impedance, and UHasselt for
concerns the use of a commercial PEDOT: PSS ink for the use of wettability and profilometer instruments. The
the production of up to 30 mm thick printed patterns on authors also thank Jie Zhang, Akash Verma, and Mohit
an innovative substrate, and the related characterization. Sharma (KU Leuven) for the fruitful discussions.
In particular, the influence of critical process parameters,
such as platen temperature and focusing ratio, on the Funding
quality of the printed features was firstly investigated for FWO, doctoral fellowship n. 1SB1120N.
a combination of ink-substrate of reference. Hereafter,
a best practice technique is established to allow direct Conflict of interest
transfer of the designated print strategy to the substrate
of interest, hence reducing time and costs associated to The authors declare no conflict of interest.
process investigation and optimization. The methodology Author contributions
bases on the assumption that, for a given ink, substrates
with comparable surface energy will behave similarly E.F., P.S.G., and E.C. guided and supervised the project.
during printing. An automated procedure to detect the E.F., P.S.G., and M.S. designed and supervised the
quality of printed lines is also proposed, as first step experiments. M.S., R.M.F., S.G., and M.R.V. conducted
toward the development of optimized and controlled experiments and contributed intellectually to the
AJ P strategies. Finally, the identified parameters for scientific design of the project. M.S. and E.F. mainly
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AJ printing on the NTE substrates (R = 2, when S = 80 wrote the manuscript. All authors contributed to the final
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f
sccm, A = 40 sccm) are applied to the target application, manuscript and provided critical feedback.
and a first prototype of the device is manufactured and
preliminarily characterized. References
New insights concerning the biocompatibility of
commercial PE inks are also learned. Despite the well- 1. Wang W, Lu Z, Li J, et al., 2020, Engineering the Biological
known biocompatibility of this material, NSCs viability Performance of Hierarchical Nanostructured Poly
assays on the selected commercial PEDOT: PSS ink (ε-Carpolactone) Scaffolds for Bone Tissue Engineering.
shows cytotoxic values ×10 more than plastic control. CIRP Ann, 69:217–20.
A dose-dependent release of toxic compounds, caused by 2. Li GN, Hoffman-Kim D, 2008, Tissue-Engineered Platforms
the residual presence of the co-solvent DEG in the printed of Axon Guidance. Tissue Eng B Rev, 14:33–51.
patterns after sintering is regarded here as the possible
cause. Hence, a surface encapsulation of the printing https://doi.org/10.1089/teb.2007.0181
patterns will be necessary to allow the applicability 3. Pires F, Ferreira Q, Rodrigues CAV, et al., 2015, Neural
of the selected ink. Alternatively, own-developed Stem Cell Differentiation by Electrical Stimulation Using
biocompatible AJ P PE PEDOT: PSS solutions should a Cross-Linked PEDOT Substrate: Expanding the use of
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be pursued. Further tests (such as electrochemical Biocompatible Conjugated Conductive Polymers for Neural
assays) and use of the intended device will be the subject Tissue Engineering. Biochim Biophys Acta, 1850:1158–68.
of future works. 4. Wilkinson NJ, Smith MAA, Kay RW, et al., 2019, A
To summarize, this study is the first step toward
the manufacturing of bioelectrical devices via AJ P Review of Aerosol Jet Printing-A Non-Traditional Hybrid
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technologies. This approach, when combined with Process for Micro-Manufacturing. Int J Adv Manuf
engineered scaffold, can open completely new possibilities Technology, 105:1–21.
and frontiers in the field of bioelectrical devices for 5. Machiels J, Verma A, Appeltans R, et al., 2021, Printed
TE applications, and in vitro testing. In this context, it Electronics (PE) as an Enabling Technology To Realize
is also to note that AJ P of collagen films has also been Flexible Mass Customized Smart Applications, Procedia
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recently demonstrated; therefore, it is possible to realize
bioelectrical applications in a single manufacturing CIRP, 96:115–20.
operation [13,14] . 6. Goh GL, Tay MF, Lee JM, et al., 2021, Potential of Printed
Electrodes for Electrochemical Impedance Spectroscopy
Acknowledgments (EIS): Toward Membrane Fouling Detection. Adv Electron
The authors gratefully acknowledge the Research Mater, 7:2100043.
Foundation Flanders (FWO) for the doctoral fellowship https://doi.org/10.1002/aelm.202100043

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