New-Tech Europe | April 2018

Origami for cells: self-folding 3D cell grippers for recording

Jordi Cools & Braeken, imec

Imec develops self-folding microgrippers that wrap around cells and func-tion as a recording shell for better cell-contact and higher signal quality. Many cell types in our body have the ability to generate electrical sig-nals, the most prominent of which include heart and brain cells. It is through the coordinated activity of these so-called electrogenic cells that the brain is capable of highly intricate information processing, and the heart can efficiently perform its function. In order to gain more profound understanding of these processes, electrophysiologists are interested in eavesdropping on the cell’s electrical conversations. Microelectrode ar-rays (MEAs) are the method of choice since this technology can comprise up to tens of thousands of electrodes that can pick up small

electrical signals, enabling parallel recording of a large number of cells. But cells whisper. The tiny signals are often only a few microvolts in am- plitude and disappear in the noise. The key way to achieve high signal quality is to maximize the cell-electrode contact and electrical coupling. Current MEA-technology, however, has reached its limitation, as it is in-herently 2D because of the wafer-based fabrication paradigm. Bridging the gap with more complex 3D interfacing, imec presents a novel multi-electrode chip with self- folding electrodes. A tale of two labs Grippers are not new. Notably, the Gracias Lab at Johns Hopkins Univer- sity (JHU) in Baltimore (USA) has a long-standing experience researching new methods to fabricate micro- and nanoscale devices with integrated structures. For example, the lab

designed self-folding microgrippers for a wide range of applications, including life sciences, such as mobile mi- crogrippers for encapsulating red blood cells or even to take small cell biopsies from living tissue. It was the ability of the self-folding structures to grasp single cells that sparked the idea for a new project between JHU and imec. The Cell and Tissue Technologies (CTT) team of imec has built up exten-sive expertise regarding in vitro recordings of electrogenic cells using MEAs. However, with the traditional, flat electrode layouts the cell-electrode contact area is limited. It became increasingly clear that 3D-interfacing is the way to go. And so the idea arose to incorporate tiny electrodes in the panels of Gracias’ microgrippers. The collaboration be- tween imec and JHU materialized in a JHU-summer internship and con- tinued in the PhD-topic of Jordi Cools, main imec-researcher on this pro-ject:

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