Marb's Lab Cooks Up a Chemical "Brain" for a Robotic Hand

Self-described "citizen scientist" Marb, of YouTube channel Marb's Lab, has built a device to demonstrate how to control a robot through chemical, rather than electronic, reactions — working towards the eventual goal of an artificial chemical brain.

"Oscillating reactions are of immense importance for life," Marb explains. "For example, they act as a clock for periodic processes like the sinus node of the heart's excitation system, or synchronized nerve activity in the brain."

In a robotic, rather than living, system, these processes are typically controlled electronically — but Marb demonstrates how that doesn't have to be the case. Initially his experiments are relatively simple, showcasing a "clock" reaction based on luminol — a chemiluminescent material that viewers of police procedurals will recognize as being used to highlight the presence of iron-containing blood at a crime scene.

After demonstrating an oscillating reaction — in which the luminol glows brightly, dims, then glows again in a predictable pattern — Marb shows how a robotic hand can be connected to an artificial chemical "brain" dubbed the Chemputer. "There are five color sensors on the PCB, one for each finger," he explains. These sensors are positioned to view five containers of luminol mixture, each of which has been mixed to exhibit the oscillating reaction from above — acting as a timer to trigger the finger's movement.

"What we haven't talked about yet is non-volatile memory," Marb notes. "This is also very easy to replicate chemically. I use a phenolphthalein solution that is either acidified or alkalized, and thus represents various non-volatile memory states."

This isn't the first unusual circuit Marb has designed: back in January this year the maker unveiled a molecular switch, flipping a spiropyran sample between two states with lasers; in August he unveiled an emulated memristor, part of an ongoing project to build a "perceptron" model of a biological neuron; and just last month he built an Arduino-driven pH meter from scratch.

The full video is embedded above, and can also be viewed on Marb's YouTube channel.