The e-Flower: A hydrogel-actuated 3D MEA for brain spheroid electrophysiology

Sci Adv. 2024 Oct 18;10(42):eadp8054. doi: 10.1126/sciadv.adp8054. Epub 2024 Oct 16.

Abstract

Traditional microelectrode arrays (MEAs) are limited to measuring electrophysiological activity in two dimensions, failing to capture the complexity of three-dimensional (3D) tissues such as neural organoids and spheroids. Here, we introduce a flower-shaped MEA (e-Flower) that can envelop submillimeter brain spheroids following actuation by the sole addition of the cell culture medium. Inspired by soft microgrippers, its actuation mechanism leverages the swelling properties of a polyacrylic acid hydrogel grafted to a polyimide substrate hosting the electrical interconnects. Compatible with standard electrophysiology recording systems, the e-Flower does not require additional equipment or solvents and is ready to use with preformed 3D tissues. We designed an e-Flower achieving a curvature as low as 300 micrometers within minutes, a value tunable by the choice of reswelling media and hydrogel cross-linker concentration. Furthermore, we demonstrate the ability of the e-Flower to detect spontaneous neural activity across the spheroid surface, demonstrating its potential for comprehensive neural signal recording.

MeSH terms

  • Animals
  • Brain* / cytology
  • Brain* / physiology
  • Electrophysiological Phenomena
  • Humans
  • Hydrogels* / chemistry
  • Microelectrodes*
  • Neurons / physiology
  • Spheroids, Cellular*

Substances

  • Hydrogels