Engineers print artificial neurons that spike

Northwestern University engineers reported in April that they had printed artificial neurons on soft, flexible sheets that can send electrical signals realistic enough to activate living mouse brain cells. The work was published in *Nature Nanotechnology* and centers on low-cost printed electronic devices built from nanosheet-based materials rather than conventional rigid silicon. In laboratory tests on slices of mouse brain tissue, the researchers said the devices produced spike-like voltage patterns that triggered responses in real neurons. The team said the results point to a route for softer brain-machine interfaces and neuromorphic hardware that more closely matches how biological nervous systems communicate. ### What exactly did the engineers print? The devices were printed artificial neurons made from molybdenum disulfide nanosheet networks, according to the *Nature Nanotechnology* paper. The study described them as memristive networks — electronic structures whose resistance changes with past activity — allowing them to generate spiking behavior instead of only simple on-off signals. Northwestern University said the artificial neurons were built from “soft, printable materials” and electronic inks, with the aim of making electronics that better match the mechanics of biological tissue. (nature.com) Mark C. Hersam, a materials scientist at Northwestern, led the study with Vinod K. Sangwan, a research associate professor at the McCormick School of Engineering, the university said. (nature.com) ### How did the devices behave like neurons? The *Nature Nanotechnology* commentary said the printed devices achieved “multi-order spiking dynamics” on physiologically relevant timescales. That means the signals were not limited to a single idealized pulse shape; instead, they reproduced a range of spike behaviors closer to those seen in living neurons. Northwestern said the artificial neurons generated electrical signals realistic enough to activate living brain cells. (news.northwestern.edu) In the mouse-tissue experiments, the university said, the voltage spikes matched key biological features including timing and duration closely enough to trigger neural activity. ### What happened in the mouse brain-cell tests? Mouse brain tissue slices were used to test whether the printed devices could communicate with living neurons, Northwestern said. (nature.com) The university reported that signals from the artificial neurons triggered responses in real neurons, demonstrating what it described as a new level of biocompatibility for printed neuromorphic electronics. (news.northwestern.edu) The *Nature Nanotechnology* paper summary said the devices could stimulate mouse Purkinje neurons, a type of neuron found in the cerebellum. That result tied the printed hardware to a specific biological target rather than only a simulated neural circuit. ### Why are soft sheets important here? Conventional chips are typically rigid, two-dimensional silicon devices, while brain tissue is soft and dynamic, Northwestern said. The researchers framed the printed films as a way to narrow that mechanical mismatch, which is a persistent problem for interfaces that aim to record from or stimulate the nervous system. (news.northwestern.edu) The university said possible applications include brain-machine interfaces and neuroprosthetics for hearing, vision and movement. (nature.com) The same work also fits into neuromorphic computing, where engineers try to build hardware that processes information more like a brain and with lower energy use than standard digital systems. Hersam said the brain is “five orders of magnitude more energy efficient” than a digital computer. (news.northwestern.edu) ### What comes next for the research? Nature Nanotechnology described the printed nanosheet networks as a platform for flexible brain-machine interfaces and bio-realistic neuromorphic hardware. The study reported laboratory results in mouse brain slices, not tests in living animals or people, so the next milestones would be further device validation, durability testing and more advanced interface experiments. That forward path is an inference from the stage of research described in the paper and university release. (news.northwestern.edu) (nature.com)