Unlocking Memories with Your Kitchen Sponge

When Harsh Jain, a researcher at the National Centre for Biological Sciences in Bengaluru, conducted an intriguing experiment involving a kitchen sponge cube, the results were nothing short of fascinating. By applying pressure to the sponge between two metal plates, Jain was able to imprint external deformities in the shape of alphabets using a motorised rod. What made this experiment even more remarkable was the fact that the sponges could remember these shapes. However, once the pressure was removed, the impressions vanished, highlighting a unique form of memory storage.

This type of memory storage, as Jain and his co-author Shankar Ghosh from the Tata Institute of Fundamental Research in Mumbai explain, differs from the elasticity found in memory foam, which cannot be reprogrammed. Their research delves into the transition of materials from an elastic regime to a 'pseudo-plastic' one, where deformations are retained due to the frictional locking of the polymeric sponge's constituent rods. This phenomenon is rooted in basic physics principles, where polyurethane rods connect and bend, creating internal friction.

"The observations we've made in soft systems have broader implications beyond our initial experiments," Jain suggests. He emphasizes the relevance of considering mechanical processes and chemical pathways when exploring biological memory. Drawing parallels with structures found in bones, wood, and leaves, Jain highlights the presence of rod networks in these biological systems, hinting at potential connections between mechanical memory and natural structures.

The emerging field of mechanical memory in biological systems focuses on how cells and cell nuclei can retain 'memories' of past mechanical environments and forces. Recent studies have shown that information can be encoded within the protein polymer network or actin cytoskeleton, which plays a crucial role in maintaining cell shape and structure. This research opens up new avenues for understanding the intricate interplay between mechanical forces and biological memory.

Looking ahead, the implications of these findings extend beyond theoretical insights. Practical applications could include the development of auxetic materials that exhibit unique properties, such as widening when stretched and narrowing when compressed. Additionally, the potential for creating reprogrammable Braille displays based on systematically designed deformation patterns showcases the versatility of this research. Arathi Ramachandran from the Indian Institute of Science (IISc) underscores the importance of experimental validation for such models, while Gondi Kondaiah Ananthasuresh from IISc advocates for further exploration into the complex mechanical properties at microscopic and atomic scales.