As researchers learn more about the human brain, they are also working to replicate some of its capabilities in technology. At Stanford University, scientists have developed artificial synapses that aim to mimic how the brain learns and processes information.
The brain contains an estimated 100 trillion synaptic connections between neurons. Synapses are the points where neurons communicate through electrical and chemical signals, which play a key role in learning and memory. Inspired by this complexity, Stanford materials scientist Alberto Salleo and his team created an artificial version of a synapse using organic semiconductors—synthetic materials that can conduct or block electricity at low cost.
Their research supports efforts to build “neuromorphic” computers, as well as new types of medical devices and neuroscience tools. Recently, Salleo’s group demonstrated a biohybrid version of their artificial synapse that can interact with living cells.
A prototype array containing nine artificial synapses showed high performance in processing speed, energy efficiency, reproducibility, and durability. The team is now able to study the microstructure of organic mixed ionic-electronic conductors (OMIECs), flexible polymer semiconductors considered promising for next-generation batteries and electronics.
Salleo explained the significance: “The artificial synapse can be used for what people call ‘brain-like computing,’ performing mathematical operations that are currently very energy inefficient in a way that’s much more energy efficient,” said Salleo, who is also deputy director for science and technology and chief research officer at SLAC National Accelerator Laboratory (SLAC) . “This is a big theme because as the demand for computation goes up, the demand for energy goes up even more. It’s becoming a major drain on the energy resources and, of course, creating all sorts of other environmental problems.”
In addition to artificial synapses, Salleo’s lab uses organic semiconducting materials to develop flexible electronics such as wearable medical devices. He noted that materials science draws from chemistry, physics, biology—and has roots in metallurgy. Historically, Stanford transformed its metallurgy program into its Materials Science and Engineering Department.
“Most people don’t know what a materials scientist does,” Salleo said. “We are the descendants of metallurgists in many ways. But as materials scientists, we work with every material, focusing on how to treat and process them to tease out the best properties.”
Salleo holds several roles at Stanford: he is the Hong Seh and Vivian W. M. Lim Professor; professor of materials science and engineering; professor in SLAC’s Photon Science Directorate; member of Stanford Bio-X; member of Wu Tsai Neurosciences Institute; and affiliate of Precourt Institute for Energy.
Stanford researchers continue work across fields such as wearable robotics—which adapt quickly to users—and virtual reality technologies inspired by early science fiction concepts. Other ongoing projects include studies on plant growth through stomata formation.
