Hydrogels have shown the ability to learn and improve their performance in the game of Pong, thanks to their unique physical properties. These materials collect a ‘memory’ of their past movements by moving ions within their structure, which then influences their future actions.
Scientists connected the hydrogels to a virtual gaming environment, using electrical signals to transmit information about the position of the ball. The movement of ions in the hydrogel was directly responsible for controlling the ‘racket’ movement.
With continuous play, the hydrogel’s accuracy improved by up to 10%, demonstrating that non-living materials can adapt and retain information. This discovery suggests the potential for a new form of ‘intelligence’ that could inspire simplified AI algorithms.
Interestingly enough, brain cells can already play Pong when electrically stimulated to get feedback on their performance. This led scientists to investigate whether non-living materials, such as hydrogels, could mimic brain-like functions.
It turns out that both brain cells and hydrogels rely on a similar mechanism: the movement and distribution of ions allows them to ‘remember’ and respond to changes in the environment. The main difference is that ions in brain cells move internally, while in hydrogels they move outward.
Hydrogels are complex polymers that become jelly-like when they come into contact with water. Common natural examples include gelatin and agar. For this study, scientists used an electroactive polymer: a hydrogel that changes shape when exposed to electric current.
This change in shape is possible due to the ions in the environment, which, when an electrical signal is applied, displace and pull water molecules, causing temporary deformation of the hydrogel.
The hydrogel contracts more slowly than it swells, meaning any ion movement is influenced by previous movements, resembling a memory process. These ions continue to move within the hydrogel based on previous rearrangements, starting from the initial creation of the material when the ions were evenly distributed.
To test the hydrogel’s ability to use its physical “memory” for actions, researchers connected it via electrodes to a virtual Pong game. They created a feedback loop between the hydrogel racket and the position of the ball.
The movement of ions in the hydrogel indicated the position of the racket, and electrical signals communicated the location of the ball to the hydrogel.
The experiment started with a random movement of the ball. During play, researchers monitored the hydrogel’s success in hitting the ball and analyzed its performance dynamics. Over time, the hydrogel improved, allowing the ball to be hit more often.
While neurons mastered the game in about 10 minutes, the hydrogel took about 20 minutes to reach the same level of skill. As the ball moved, the gel stored information about its trajectory and used this data to position the racket for optimal hits. The movement of ions created a “memory” of past actions, ultimately increasing the effectiveness of the system.
Most current AI algorithms are based on neural networks, but researchers suggest that hydrogels could represent an alternative form of ‘intelligence’ that could provide new, simpler algorithms. Future studies will delve deeper into the hydrogel’s memory mechanisms and assess its potential to perform other tasks.
The research was published in Cell reports natural sciences.
