New class of soft materials process logic using beams of light

by Clarence Oxford
Los Angeles CA (SPX) Nov 21, 2025

Researchers from McMaster University and the University of Pittsburgh have created the first functionally complete NAND gate in a soft material using beams of visible light. Published in Nature Communications, the work establishes a major contribution to the concept of materials that compute, where the material itself processes information without conventional electronic circuits.

Fariha Mahmood, the paper's first author and a postdoctoral researcher at Cambridge, recounted, "To see these materials not only respond to light but also perform a logic operation feels like watching the material 'think.' It opens the door to soft systems making decisions on their own." Mahmood worked with Anna C. Balazs, Victor V. Yashin, and Kalaichelvi Saravanamuttu on the project.

Experiments confirmed that directing three self-trapped light beams into a purpose-developed hydrogel reliably executes the NAND logic necessary for all other digital logic gates. The result positions photoresponsive soft materials as autonomous, computation-capable platforms.

Earlier foundational work by Balazs and her late collaborator Steven P. Levitan introduced the theoretical groundwork for materials that compute-systems capable of performing tasks like pattern recognition and decision-making without traditional circuitry.

"This is what we've always imagined-materials that don't just respond to a stimulus, but process it," Balazs said. "It's a realization of a concept that soft materials can carry out simple operations typically done by electronics."

The merocyanine-functionalized hydrogel contracts under illumination, increasing its refractive index and causing light beams to self-trap within the material. Previous work showed that two light beams compete and inhibit each other; the current study found that adding a third beam produces stable logic behavior. "The middle beam is always dimmer because it's fighting both of its neighbors. That reliable behavior is what lets us map a logic operation onto a soft material," Mahmood stated.

Saravanamuttu commented on the broader implication: "We're showing that computer logic-something usually thought of as the domain of electronics-can be performed by a material through its own chemistry and physics."

Although not competitive with silicon processors in speed or data density, the significance is clear in applications requiring independent decision-making by materials. Target areas include soft robotics, self-regulating medical devices, sensors in inaccessible environments, and adaptive materials.

Balazs added, "These systems don't aim to replace silicon-they aim to mimic the remarkable autonomy of biological materials. A soft material that can sense, compute, and respond on its own opens entirely new design spaces." The gel platform also enables parallel logic operations, as all input and output signals are beams of light that can be routed and combined without wiring.

Reflecting on the achievement, Balazs said, "Steven believed deeply that materials could someday compute. To see that vision realized experimentally is incredibly meaningful."

Research Report:A functionally complete logic gate in a soft photoresponsive hydrogel