Science & Technology, Australia (Commonwealth Union) – Engineers from Macquarie University have introduced an innovative method to significantly reduce the carbon footprint, cost, and enhance efficiency and adaptability in manufacturing nanosensors. This advancement marks a substantial improvement in a trillion-dollar global industry by revolutionizing a critical production process.
The team’s breakthrough involves treating each sensor with a single drop of ethanol, deviating from the traditional technique that entails subjecting materials to high temperatures. This innovative approach is detailed in their recent research publication titled ‘Capillary-driven self-assembled microclusters for highly performing UV detectors’, released 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,” explained the corresponding author Associate Professor Noushin Nasiri, who is head of the Nanotech Laboratory at the Macquarie University, School of Engineering.
Nanoparticles come together to form a network connected by weak natural bonds. However, this can lead to gaps between the nanoparticles that prevent the transmission of electrical signals. Consequently, the sensor becomes non-functional.
Associate Professor Nasiri’s team stumbled upon this discovery while enhancing ultraviolet light sensors, a technology pivotal to Sunwatch, which propelled Nasiri to become a finalist for the 2023 Eureka Prize.
Nanosensors possess an extensive surface-to-volume ratio, comprising layers of nanoparticles, rendering them remarkably sensitive to the substances they are designed to detect. Nonetheless, the majority of nanosensors remain inactive until subjected to a 12-hour, energy-intensive process involving high temperatures. This process fuses the nanoparticle layers, creating pathways for electrons to traverse, thereby enabling sensor functionality.
Unfortunately, this furnace-based approach destroys most polymer-based sensors, and nanosensors featuring minute electrodes, akin to those in nanoelectronic devices, risk melting. According to Associate Professor Nasiri, the existing limitation lies in the inability of many materials to endure high temperatures.
However, the Macquarie team’s groundbreaking technique circumvents this heat-dependent procedure. Consequently, nanosensors can be crafted from a wider spectrum of materials, expanding their potential applications.
The application of a single droplet of ethanol onto the sensing layer, without the need for an oven, the atoms on the nanoparticle surface gain mobility. This results in the fusion of particles, closing the gaps between them as indicated by Associate Professor Nasiri.
“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 novel technique emerged when Jayden (Xiaohu) Chen, a postgraduate student and the study’s lead author, unintentionally spilled ethanol onto a sensor while cleaning a crucible. This event, which would typically render these delicate devices useless, led to an unexpected discovery.
Chen indicated that at 1st, it was believed the sensor was ruined, but he later noticed that the sample was actually performing better than any other we had produced before.
Associate Professor Nasiri highlights that while the accident sparked the idea, the efficacy of the method hinged on meticulous efforts to determine the precise volume of ethanol applied.
She further indicated that when Jayden discovered this outcome, they embarked on a meticulous process of experimenting with various ethanol quantities. He conducted numerous tests in a dedicated effort to pinpoint the effective approach.
“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 team has patent applications in progress for this breakthrough, which could have a substantial impact on the realm of nanosensors.
Associate Professor Nasiri confirms that they have formulated a method for ensuring the functionality of nanosensors, and they have validated it not only with UV light sensors but also with nanosensors designed to identify carbon dioxide, methane, hydrogen, and other substances. The results are consistently positive.
