People can readily share images and sounds digitally, as evidenced by the billions of smartphones in use globally that often overload the human senses of sight and hearing. But smell generally remains missing from remote communication. That could soon change.
Researchers have developed technology that features an electronic nose that recognizes certain smells, like the distinctive aroma of coffee, and then instructs a small and wearable remote device to release scent molecules matching it. The digital communication can take place at any distance, from across the room to around the world.
"In simple terms, it connects 'smelling something here' with 'recreating the corresponding smell somewhere else,'" said Chunyu Yang, an Ohio State University doctoral student in materials science and engineering and lead author of a study describing the technology published in the journal Science Advances.
"The idea is to add smell to the visual and audio information we already share remotely, making those experiences more engaging," Yang said.
The researchers call this latest development in the field of digital scent technology "Scentronic."
"What makes Scentronic different is that it brings odor sensing and generation together for remote sharing. To the best of our knowledge, our study is the first to explore this integration in a compact platform for remote odor sharing," Yang said.
The researchers created an e-nose, a device that uses an array of gas sensors to detect chemical compounds associated with different odors. A machine-learning model then classifies odors that the e-nose has been trained to recognize — beer, cake, coffee, oranges and red wine.
The technology uses an online platform to transmit the odor information to a scent generator, which then releases fragrances to recreate the aroma at the receiving end. The scent molecules themselves are not transmitted over the internet.
The e-nose device is roughly 6 inches (15 centimeters) in diameter and is portable, though not designed to be worn. The researchers developed several versions of the odor generator, including wristband, necklace and handheld designs.
'Everyday odors'
At this point, the e-nose recognizes just the five scents.
"We chose these because they are familiar everyday odors with different scent profiles, making them useful examples for demonstrating the system. We have not yet expanded beyond those categories," Yang said.
"A broader scent library is possible in principle, but an unlimited repertoire is far beyond what we have demonstrated. Recognizing an odor and accurately reproducing it are separate challenges. Covering a useful range of everyday scents is a more realistic goal, although that would still require substantial development," Yang said.
The receiving device cannot recreate every smell Scentronic encounters.
"To support additional odors, we would need to train the electronic nose to recognize them and provide corresponding scented liquids in the odor generator," Yang said.
The researchers see various potential applications for the technology.
"For example, someone could share the scent of a meal with family or friends who live far away. Other potential applications include more immersive virtual and augmented reality experiences and online shopping that allows customers to sample selected scents remotely," Yang said.
'A research prototype'
The research was conducted and the devices developed without the involvement of a company, Yang said.
"At present, this is a research prototype. Moving toward commercialization would require a larger, more diverse training dataset and reliable odor recognition under real-world conditions, where smells often occur in mixtures," Yang said.
"The odor generator would also need further development to support more scents while remaining compact and convenient to use. Other considerations include scent fidelity, refillability, durability, manufacturing costs and the safety of repeated exposure to the scented mist," Yang said.
Smartphones are becoming increasingly capable. Could they in the future incorporate scent technology so that, for instance, a person at a tailgate party before an Ohio State football game could call a friend and share video, audio and the aroma of hot dogs on the grill?
"In principle, a smartphone could connect to a scent-generating accessory. Integrating everything into the phone itself would be more challenging because the scent reservoirs, electronics and atomizers all take up space and add weight. Miniaturization and convenient refilling would be important considerations," Yang said.
"The tailgate example illustrates the idea well. A future system could potentially combine video and audio with a corresponding scent, provided it could recognize the relevant odor and the receiver had a suitable scent formulation available. Our current system has not demonstrated the transmission of a grilling-hot-dog scent or the exact mixture of smells at a tailgate party," Yang said.