A new method to make the manufacture of nanosensors far less carbon-intensive, budget-friendly, highly efficient, and versatile has been developed by engineers from Macquarie University, thereby considerably enhancing a main process in this trillion-dollar global industry.
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The team has discovered a method to treat each sensor by making use of a single drop of ethanol rather than the traditional process that includes heating materials to high temperatures.
Their study was published in the Journal of Advanced Functional Materials.
Nanosensors are usually made up of billions of nanoparticles deposited onto a small sensor surface–but most of these sensors don’t work when first fabricated.
Noushin Nasiri, Study Corresponding Author and Associate Professor, Head of the Nanotech Laboratory, School of Engineering, Macquarie University
The nanoparticles collect themselves into a network held collectively by weak natural bonds, which could leave several gaps between nanoparticles where they fail to send electrical signals, leading the sensor not to function.
Associate Professor Nasiri’s team discovered the finding while working to enhance ultraviolet light sensors, the main technology behind Sunwatch, which saw Nasiri become a 2023 Eureka Prize finalist.
Nanosensors consist of a huge surface-to-volume ratio composed of layers of nanoparticles, thereby making them highly sensitive to the substance they have been developed to detect.
However, most nanosensors do not work efficiently until heated in a tedious and energy-intensive 12-hour process by using high temperatures to fuse layers of nanoparticles, thereby making channels that enable electrons to pass through layers so the sensor will function.
The furnace destroys most polymer-based sensors, and nanosensors containing tiny electrodes, like those in a nanoelectronic device, can melt. Many materials can’t currently be used to make sensors because they can't withstand heat.
Noushin Nasiri, Study Corresponding Author and Associate Professor, Head of the Nanotech Laboratory, School of Engineering, Macquarie University
But the new method discovered by the Macquarie group bypasses this heat-intensive process, thereby enabling nanosensors to be made from a highly extensive range of materials.
Adding one droplet of ethanol onto the sensing layer, without putting it into the oven, will help the atoms on the surface of the nanoparticles move around, and the gaps between nanoparticles disappear as the particles to join to each other.
Noushin Nasiri, Study Corresponding Author and Associate Professor, Head of the Nanotech Laboratory, School of Engineering, Macquarie University
Nasiri added, “We showed that ethanol greatly improved the efficiency and responsiveness of our sensors, beyond what you would get after heating them for 12 hours.”
The new technique was found after the study’s lead author, postgraduate student Jayden (Xiaohu) Chen, accidentally splashed ethanol onto a sensor while washing a crucible in an incident that would generally ruin such sensitive devices.
Chen stated, “I thought the sensor was destroyed, but later realized that the sample was outperforming every other sample we’ve ever made.”
Associate Professor Nasiri states that the accident may have provided them with the idea, but the effectiveness of the method relied on painstaking work to determine the exact volume of ethanol utilized.
Nasiri stated, “When Jayden found this result, we went back very carefully trying different quantities of ethanol. He was testing over and over again to find what worked. It was like Goldilocks–three microlitres was too little and did nothing effective, 10 microlitres was too much and wiped the sensing layer out, five microlitres was just right!”
The research group has patents pending for the breakthrough, which could make a very big splash in the world of nanosensors.
“We have developed a recipe for making nanosensors work and we have tested it with UV light sensors, and also with nanosensors that detect carbon dioxide, methane, hydrogen, and more—the effect is the same,” stated Associate Professor Nasiri.
Nasiri added, “After one correctly measured droplet of ethanol, the sensor is activated in around a minute. This turns a slow, highly energy-intensive process into something far more efficient.”
Already, Associate Professor Nasiri has been approached by companies in Australia and internationally who are keen to function with her to put the method into practice.
Journal Reference
Chen, X., et al. (2023) Capillary-Driven Self-Assembled Microclusters for Highly Performing UV Photodetectors. Advanced Functional Materials. doi.org/10.1002/adfm.202302808.
Source: https://lighthouse.mq.edu.au/