Caleb Sooknanan ‘20

Microelectrode arrays or MEAs are electrode systems that can be used to analyze electric signals among cardiac cells and neuronal cells, repair sensory abilities among human patients, and address nervous system disorders. However, most of the devices currently associated with MEAs rely on silicon or polymer substances, which make it difficult for scientists to mimic the structural and functional capabilities of living tissue. Doctor Bernhard Wolfrum and researchers from the Technical University of Munich in Germany proposed a new method by which soft MEAs could be produced and used as bioelectronic interfaces. The researchers evaluated the effectiveness of this approach by printing high resolution carbon MEAs on various surfaces; the researchers also assessed whether the MEAs could record electric signals from different cells.

To print the microelectrodes array interfaces, the researchers utilized nanoparticle inks and a high-resolution inkjet printer, a printer that recreates digital images by propelling ink droplets onto paper or other mediums. The researchers designed electrode microchips — each consisting of 64 carbon electrodes — with nanoparticle ink derived from silver and carbon. The researchers then printed MEAs on soft substrates such as polydimethylsiloxane or PDMS, agarose, and gelatin-like substances such as gummy bears that were melted and allowed to harden before the printing process. The researchers then evaluated the functional effectiveness of their MEAs by recording action potentials from HL-1 cardiac muscle cells, which were cultured in the MEAs until a cell layer could be developed and analyzed with fluorescent stains.

According to the study’s results, the HL-1 cells within the MEA cultures were spontaneously contracting a few days after placement in their cultures; the printed MEA devices were therefore compatible with the active cardiac muscle cell layer. Also, the researchers suggested that MEAs developed using inkjet printing could overcome stability difficulties that would otherwise originate printing structures with different spatial scales. More work is needed to understand how MEAs could be directly produced on gelatin materials removed from organisms and eventually transplanted onto living tissue. Nevertheless, the researchers suggested that such devices may yield rapid prototyping of sensor array structures on a wider variety of surfaces.

References

1. B. Wolfrum, et. al., Printed microelectrode arrays on soft materials: from PDMS to hydrogels. Nature Partner Journals Flexible Electronics 2 (2018). doi: 10.1038/s41528-018-0027-z.  
2. Image retrieved from: https://images.pexels.com/photos/54633/gummibarchen-fruit-gums-bear-sweetness-54633.jpeg?auto=compress&cs=tinysrgb&dpr=2&h=650&w=940