Researchers have utilized vinegar vapor to significantly enhance UV sensors through an inexpensive, room-temperature method, which could lead to improved wearable technology.
Scientists at Macquarie University have introduced an innovative technique for creating ultraviolet (UV) light sensors, potentially resulting in more efficient and adaptable wearable devices.
The findings, published in the journal Small in July, reveal how acetic acid vapor—essentially the fumes from vinegar—can quickly boost the effectiveness of sensors made from zinc oxide nanoparticles without the need for high-temperature processing.
Co-author Professor Shujuan Huang from the School of Engineering at Macquarie University explains: “By briefly exposing the sensor to vinegar vapor, adjacent zinc oxide particles on the sensor’s surface bonded together, forming conductive bridges.”
Connecting zinc oxide nanoparticles is crucial for building tiny sensors, as it creates pathways that allow electrons to flow.
The research team discovered their vapor method could increase the responsiveness of UV detectors by 128,000 times over untreated ones, while still accurately detecting UV light without interference, resulting in highly sensitive and trustworthy sensors.
Associate Professor Noushin Nasiri, co-author of the study and head of the Nanotech Laboratory at Macquarie University, states: “Traditionally, these sensors are processed in an oven at high temperatures for around 12 hours before they can function or send any signals.”
However, the team discovered a straightforward chemical approach that mimics the effects of heat processing.
“We found a method to treat these sensors at room temperature using a low-cost ingredient—vinegar. Simply exposing the sensor to vinegar vapor for five minutes results in a functioning sensor,” she adds.
To fabricate the sensors, the researchers sprayed a zinc solution into a flame, creating a fine mist of zinc oxide nanoparticles that settled onto platinum electrodes. This created a thin, sponge-like film, which was then exposed to vinegar vapor for five to twenty minutes.
The presence of vinegar vapor altered the arrangement of the tiny particles in the film, helping them connect, facilitating electron flow through the sensor. Meanwhile, the particles remained small enough to effectively detect light.
“These sensors consist of numerous tiny particles that need to link together for the sensor to function,” explains Associate Professor Nasiri.
“Before we treat them, the particles merely sit beside each other as if encased in a wall. When light generates an electrical signal in one of the particles, it struggles to move to the next particle. That’s why untreated sensors yield inadequate signals.”
The researchers conducted thorough testing of various formulations before discovering the ideal balance in their procedure.
“Water alone is not potent enough to bond the particles, while pure vinegar is too strong and damages the entire structure,” explains Professor Huang. “We needed to find the perfect combination.”
The study indicates that the most effective results arose from sensors that were exposed to the vapor for about 15 minutes. Longer exposure resulted in too many structural alterations, leading to decreased performance.
“The distinct structure of these highly porous nanofilms permits oxygen to penetrate deeply, making the entire film integral to the sensing mechanism,” notes Professor Huang.
This new room-temperature vapor technique offers several benefits over traditional high-temperature methods. It accommodates heat-sensitive materials and flexible bases, is more cost-effective, and has a reduced environmental impact.
Associate Professor Nasiri emphasizes that the process can be easily scaled for commercial use.
“The sensor materials could be arranged on a moving plate, passing through a space filled with vinegar vapors, becoming ready for use in less than 20 minutes.”
This method presents a significant advantage for creating wearable UV sensors that require flexibility and minimal power consumption.
Associate Professor Nasiri suggests that this UV sensor approach could also be applied to other sensor types, utilizing simple chemical vapor treatments instead of high-temperature processing across a variety of functional materials, nanostructures, and substrates.
