How can what engineers learn from how barn owls pinpoint the location of the faintest sounds apply to their development of nanotechnologies capable of doing even better? In episode 61, we’re joined by Saptarshi Das, a nano-engineer from Penn State University, who talks with us about his open-access article “A biomimetic 2D transistor for audiomorphic computing,” co-authored with Sarbashis Das and Akhil Dodda, and published on August 1, 2019 in the open-access journal Nature Communications.

Hearing Better than a Barn Owl - Saptarshi Das
Hearing Better than a Barn Owl - Saptarshi Das
Hearing Better than a Barn Owl - Saptarshi Das Hearing Better than a Barn Owl - Saptarshi Das
@rwatkins says:
Next time, in episode 62 of Parsing Science, we’ll be joined by Dimitris Xygalatas from the University of Connecticut’s Department of Anthropology. He’ll talk with us about his research into an extreme ritual involving pain and suffering … but that has no discernible long-term harmful effects on its practitioners, and may actually positively impact their psychological well-being.
@rwatkins says:
Saptarhi’s tiny device seemed to us to have a wide range of possible uses, such as enhancing existing assistive devices like hearing aids or augmenting listening devices used to detect and locate victims trapped in debris following natural disasters. So we wrapped up by asking Saptarshi what he sees as the device’s potential applications.
@rwatkins says:
While the barn owl excels in its ability to determine the location of sound in complete darkness, Ryan and I wondered if it might be possible for Saptarshi’s device to exceed the fidelity of barn owls’ hearing. Here’s what he had to say about the question.
@rwatkins says:
It seemed to Doug and me that faster would be better when it comes to processing the directionality of sound, so we were interested in learning why it’s necessary to have neurons which delay the arrival of sound in the first place.
@rwatkins says:
Probably the best-known version of Moore’s Law - named after Gordon Moore, the current CEO of Intel - is that the number of transistors in a computer chip doubles on a scale of every two years or so. 2D devices stand to drastically shrink the size of computers’ integrated circuits. But there’s more to computer chips’ evolution than scaling of their size. So Doug and I were curious how this relates to Saptarshi’s interest in developing 2D nano-transistors.
@rwatkins says:
The activation of neurons related to delay and co-incidence are essential for how the barn owl locates the direction from which the sound of its prey came. Mimicking this in a 2D nano-transistor required building multiple split-gates with gaps of varying widths to determine which of its digital neurons fired when a sound triggered the electrical charge. Here, Saptarshi explains how he and his team were able to manipulate nanomaterials to create such circuits.
@rwatkins says:
Saptarshi’s biomimetic device is unique in that it combines digital and analog computation, which is abundant in biological neural networks. Its resistors provide the circuit’s digital functionality by working in pairs to determine if one of five computational neurons is switched on or off. Its analog functionality is accomplished by both the spacing between the circuit’s contact points ... along with a gate which tunes the device by altering the conductivity between those points … mimicking the way in which animals can be more attentive when necessary to localize a sound’s direction, and less so when not. We asked Saptarshi how the device functions both like a delay and co-incidence neuron.
@rwatkins says:
Saptarshi and his team created a device comprised just resistors and capacitors, called an RC circuit ... but at a nano-scale just atoms in thickness, qualifying it as being two - rather than three - dimensional. The device was designed to mimic mathematical models of animals’ sound localization systems developed in the 1940s by the acoustical scientist Lloyd Jeffress. So we were interested in learning how - and why - he was motivated to apply that model to this 2D device.
@rwatkins says:
The animal able to hear the highest frequencies is the greater wax moth. It was long thought that they evolved this ability to hear the ultrasonic sonar emitted by their biggest predator: bats. Especially since this hypothesis was debunked by a team of scientists led from the University of Florida earlier this month, Doug and I wondered what makes the auditory cortex of barn owl the standard by which excellence in hearing is gauged.
@rwatkins says:
We all can probably remember back to learning about how having two ears allows animals to have stereoscopic hearing capable of localizing the direction a sound is coming from. For example, if you’re wearing headphones right now, you should have no problem hearing these rattles being moved from right to left around your head ... While we might also be familiar with how the hammer, anvil and stirrup bones amplify sound in the inner ear, we may not have learned how the brain processes these neural signals, so Ryan and I asked Saptarshi to explain how auditory information processing works.
@rwatkins says:
Sometimes the best solutions to problems aren’t always the most complex, nor are the best answers necessarily new ones. And the evolution of the natural world provides millennia of evolutionary trial-and-error experiments from which we can learn. Saptarshi’s research lab focuses on developing nanodevices which often seek solutions to human challenges by imitating processes found in nature. We started our conversation by asking Saptarshi how he got interested in this design philosophy, called “biomimicry.”
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Websites and other resources

    • (a) Optical image of Saptarshi’s device, and (b) zoomed in scanning electron microscope (SEM) image (false colored) of a biomimetic device for imitating the neural computational map inside the auditory cortex of barn owl [from the article]:

    • (a) Schematic of the biomimetic device, where VSG1 and VSG1 indicates the split-gate voltage, VDS the drain bias voltage, IDS the source to drain current, and VBG the back-gate bias [from the article]:

Media and Press
 

Penn State | Futurity | Science Daily | Innovation Toronto | AAAS EurekAlert

 
 

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Hosts / Producers

Ryan Watkins & Doug Leigh

How to Cite

Watkins, R., Leigh, D., & Das, S.. (2019, Oct. 29). Parsing Science – Hearing better than a barn owl. figshare. https://doi.org/10.6084/m9.figshare.10157003

Music

What’s The Angle? by Shane Ivers

Jhirijhiri (binaural recording) by Subhashish Panigrahi [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)]

Transcript

Saptarshi Das: that’s a fascinating aspect: that you can learn from nature which has already, you know, fine-tuned these kind of neurobiological devices for the survival of these animals.

Ryan Watkins: This is Parsing Science the unpublished stories behind the world’s most compelling science as told by the researchers themselves. I’m Ryan Watkins.

Doug Leigh: And I’m Doug Leigh. Today, in episode 61 of Parsing Science, we’re joined by Saptarshi Das from Penn State University. He’ll discuss his research into engineering a device for determining a sounds location that’s inspired by the way barn owls precisely determine where sound is coming from to track their prey in the dark … And his device is so small it exists only in two, rather than three, dimensions. Here’s Saptarshi Das.

Das: Hi, this is Saptarshi Das. And I was actually born in India, in a town called Kolkata. Most of my studies in high school and under graduation took place in Kolkata. I graduated with a degree in electronics and telecommunication engineering from Jodhpur University. And after that I directly came to the United States to pursue my doctoral degree. I joined Purdue University, the Electrical and Computer Science Department. And there I was mostly working on micro and nano-electronics, working with new materials, novel devices, and trying to resolve some of the critical issues that we face with energy efficiency of electronic devices. I finished my PhD degree in 2013 from Purdue, and after that I moved to Argonne National Lab for a postdoctoral study. I joined Penn State in 2016 as an assistant professor in the Department of Engineering Science and Mechanics. And it’s already been like three and a half years now. In Penn State we are currently working on novel devices for the next generation of computing, because there are some severe limitations that we are currently facing. And we [are] using new materials – mostly the two-dimensional materials – and devices based on them to resolve those issues.

Watkins: Sometimes the best solutions to problems aren’t always the most complex, nor are the best answers necessarily new ones. And that evolution of the natural world provides millennia of evolutionary trial and error experiments from which we can learn. Saptarshi’s research lab focuses on developing nanodevices which often seek solutions to human challenges by imitating processes found in nature. We started our conversation by asking Saptarshi how he got interested in this design philosophy, called biomimicry.

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