intelligent molecules for brain-like devices
The human brain is the most energy-efficient 'computer' there is, but it cannot easily be copied with binary electronics. Professor Christian Nijhuis has succeeded in creating a molecular switch that learns from the past and thus imitates the analogous information transfer in the brain.
Nijhuis is now looking for similar structures and trying to get these molecules to work together in a network. This brings energy-efficient computers that mimic our brains one step closer. ‘There is a fantastic molecular computer between our ears,’ says Nijhuis. ‘And it is extremely energy efficient too. This is in increasing contrast to today’s (super) computers and data centers, which need enormous amounts of energy.’
Because everything in electronics is getting smaller, scientists are investigating ever smaller building blocks, as small as molecules that can function as switches. Nijhuis was especially inspired by nature, because of the energy efficiency of natural molecules. However, a promising molecule called HATNA initially did not seem to work well as a switch.
‘We saw dynamic behavior: whether the molecule turned ‘on’ or ‘off’ seemed to depend on what had happened before,’ he says. ‘I realized that this was not a problem, but rather a solution: the behavior of the molecule showed a form of memory, just like the ‘switches’ in our brains. With the HATNA molecule we can potentially make a device that processes information in the same way as our brains do: through pulses that brain cells transmit to each other via synapses. And that is infinitely more efficient than the binary processing of ones and zeros in computers.’
The breakthrough his group published in Nature Materials in 2022, earned Nijhuis a lot of media attention, but this was preceded by a period of intensive research. From the first experiments with the HATNA molecule to fully understanding how this molecule switches, took the researchers more than two years, says Nijhuis: ‘A molecular switch like this can become the basis for a molecular computer, especially in applications where computing power should only consume little energy, such as self-driving cars. And because the molecule is biocompatible, it may also be suitable for medical applications, such as electronic implants.’
Before this work leads to an actual molecular computer, there are still some obstacles to overcome, Nijhuis thinks. ‘We can now make one switch and we understand how it works. The next steps are to increase the switching speed and to connect multiple switches working together in a robust neural network,’ he says. ‘There are still some challenges in manufacturing such a network of switches.’
There are also other challenges, in different fields of research. For example, hardware in a brain-like computer is completely different than in a traditional computer. This also requires different algorithms to use the computer. A multidisciplinary approach is essential. Nijhuis: ‘We collaborate a lot, also with the industry. Within the university we participate in the Molecules Center and Center for Brain-Inspired Nano Systems (BRAINS), which is a global leader in the development of efficient new computer hardware based on biological-inspired neuronal networks. This research on charge transfer in and between molecules is very fundamental and takes quite some time. It is nice to see that it eventually leads to promising applications.’
Education
Because Nijhuis is still relatively new in Twente, setting up his chair has had a bit more priority than his educational tasks. Of course, within his research group he mentors several people in different phases of their studies. ‘Students and PhD candidates are the beating heart of a research group,’ he says. Nijhuis works at the intersection of chemistry and physics and is involved in both courses. He teaches various courses in the Chemical Science & Engineering (CSE) and Applied Physics courses. In addition to education within the university, Nijhuis believes it is important to let the rest of society know what he is doing as a scientist. He regularly gives guest lectures and talks, for example at the Science Café in Enschede. In September 2023, Nijhuis won the MESA+ Outreach Award for these activities.
About Christian Nijhuis
Christian Nijhuis studied chemistry in Groningen and obtained his PhD in supramolecular chemistry at the University of Twente. After a postdoc period at Harvard, Nijhuis worked at the National University of Singapore for ten years. In 2020, he became professor of Hybrid Materials for Opto-electronics at the Faculty of Applied Sciences in Twente. Nijhuis received a Vici grant from NWO in 2023 for his research into smart molecules for brain-like electronics.
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