Implantable carbon microelectrodes allow the rapid detection of neurotransmitters in the brain. There are different fabrication strategies for such microsensors, but it is still challenging to customize their sizes and shapes.

B. Jill Venton, University of Virginia, Charlottesville, USA, and colleagues have fabricated 3D-printed, freestanding carbon microelectrodes in different shapes. Direct laser writing, a nano-3D-printing technique, was used to shape a photopolymer on a tiny metal wire into the desired electrode shape, e.g., a sphere or a cone. After the shaping process, the polymer was pyrolyzed to give the carbon electrodes. The laser writing method provides a sub‐micron resolution and, thus, can produce custom designs down to the sub‐micron scale.

The 3D-printed microelectrodes showed promising electrochemical properties. They were successfully implanted into rat brains to detect the release of the neurotransmitter dopamine. According to the researchers, the method is promising for batch‐manufacturing customized sensors with rationally designed shapes and sizes for different applications.

• 3D-printed carbon electrodes for neurotransmitter detection,
  B. Jill Venton, Cheng Yang, Qun Cao, Pumidech Puthongkham, Scott T. Lee, Mallikarjunarao Ganesana, Nickolay V. Lavrik,
  Angew. Chem. Int. Ed. 2018.
  https://doi.org/10.1002/anie.201809992