Computers spend a large share of their energy moving data between a processor and a separate memory. Engineers have tried to copy that compact style of computing with devices called artificial synapses, which are tiny electronic junctions that change how easily current flows after each electrical pulse, much as a biological connection between neurons grows stronger or weaker. Most earlier versions used rigid silicon and metals. Those parts need expensive vacuum factories and later become electronic waste that is hard to recycle.
Researchers at Suzhou University of Science and Technology printed flexible artificial synapses, from liquid inks at room temperature. The finished devices can be dissolved on purpose in about six minutes. The result is meant to show that brain-like hardware, often called neuromorphic hardware because it borrows the brain’s habit of mixing memory and computation in one place, does not have to rely on rare metals or chips that last forever.
The material is a hydrogen-bonded organic framework, an orderly stack of ring-shaped porphyrin molecules held together by weak attractions known as hydrogen bonds. A voltage pulse parks electric charge in pockets in the stack and raises conductance, which is how easily current flows. The opposite pulse resets the junction. The change takes 26 nanoseconds and can take ten distinct levels.
A printed grid that learns and vanishes
A 10 by 10 grid on a flexible polyimine plastic sheet, a polymer that can later be chemically taken apart, recognized handwritten digits with 97.23 percent accuracy. It still worked after 200 tight bends. A warm chemical bath then breaks the sheet into soluble monomers, the small units that make up a polymer, in about six minutes. The inks could be sprayed or inkjet-printed, which may suit short-lived medical patches that process signals on the skin and then disappear.
This research is published in the International Journal of Extreme Manufacturing.