A nose for technologies of the future

A new high-tech face mask makes a virtual stroll through an orchard spring to life via the fresh fragrance of apples. Integrated with virtual reality (VR) software, scented paraffin waxes in the mask produce 30 smells on demand, from rosemary and fruity pineapple, to sweet pancakes.

Not everything is an olfactory delight, however. The device can also recreate the controversial aroma of durian, a fruit which some say smells like a cross between garbage, sewage, and sweaty socks. The mask is just one of many futuristic technologies under development at City University of Hong Kong (CityU), including next-generation radio antennas and high-capacity batteries.

“Our work reports the first wearable system that generates smells for VR users with ultra-fast response times,” says Xinge Yu, a CityU biomedical engineer who led a team that recently detailed their technology in Nature Communications¹.

The smell-integrated VR system can also be delivered via a thin, flexible patch attached to the upper lip, albeit offering fewer scents. “We think it greatly aids progress in building up immersive virtual worlds,” he says.

Good smells

At CityU, researchers including Yu are at the forefront of next-generation electronics. These include devices that could conjure up ‘holograms’ of people speaking on the other end of the phone, or which can release good and bad smells to help people choose meals from a menu, or to remind them that the bins need to be emptied.

Many of these devices may soon be fast-tracked into commercial products thanks to the university’s comprehensive support system. Backed by ultra-modern labs and teaching facilities, the researchers behind the technologies are also addressing critical global challenges and extending the frontiers of knowledge.

“CityU’s support, in terms of funding, resources and industry connections, allows the transformation of our innovative technology into practical applications,” says Chi-hou Chan, Chair Professor of Electronic Engineering. “The research environment here is conducive to the free flow of research ideas.”

Chan’s team has used that support to help develop an advanced antenna that produces highly-controllable beams of electromagnetic radiation which will have applications in 6th generation (6G) of wireless communications.

Advancing communications

The antenna is made of an array of ‘meta-atoms’, metallic nanostructures that can act as very high-speed switches to redirect light and other wavelengths of electromagnetic radiation. The switches offer the researchers unprecedented, simultaneous control over all the parameters of the radiation produced by the antennas.

“Most antennas are passive,” Chan explains, meaning that they only produce radiation with fixed parameters such as frequency, amplitude or direction. The design from Chan’s team allows control over all five parameters simultaneously, also including phase and polarization.

“This design offers distinct advantages over conventional transmitter architectures, providing a simpler structure, while enhancing security against eavesdropping,” Chan says.

The research, published in Nature Electronics², marks a “remarkable advance in wave science,” says Chan. For example, the researchers think that a two-dimensional array of the antennas could manipulate light in more sophisticated ways, perhaps even to create holographic projections of pictures. They have applied for a patent and are exploring how to transfer the antenna to market.

Commercialization efforts have been hastened by the move in 2008 to award the lab the title of State Key Lab of Terahertz and Millimeter Waves (SKLTMW). This made it the first engineering key state facility in Hong Kong with research focused on antennas, microwaves, and millimetre-wave circuits. The long-term goal of the SKLTMW, Chan says, is to use basic and applied research to advance communication technologies.

Clean energy contributions

Related research at CityU is also well placed for wide-reaching impacts, including a new battery material that overcomes a persistent technical challenge and can lead to significantly higher energy storage capacity.

Published in Nature Energy³, the discovery was led by physicists, Yang Ren and Qi Liu, who along with international collaborators developed new cathode materials that could lead to longer-lasting and more efficient lithium-ion batteries.

Rich in lithium and manganese oxides, these cathode materials are cheap and allow batteries with high capacity. But their real-world use has been hindered because they rapidly lose power during recharge. The CityU project has addressed this by finding a way to stabilize the unique honeycomb structure of the oxides, resulting in a battery that retained 96% of its capacity after 50 cycles.

Another breakthrough at CityU’s chemistry department, recently published in Nature⁴, should help with a key plank in the transition to clean energy. A team led by chemist, Hua Zhang, developed new ways to make catalysts that create hydrogen gas from water, offering a source of the fuel that can now be used to power vehicles and other energy-intensive tech.

These are just a few examples of the forward-thinking approach of CityU researchers, which is further supported by the way that the university attracts early-career scientists, says Yu, who started out as one himself in 2018.

“The university provides a lot of support to researchers and encourages cooperation among young scientists, knowledge transfer, and provides sufficient research resources,” he says.

Commercialization boost

Yu, who is behind the smell-integrated VR technology, hopes that — rather than just using it for entertainment — it could one day serve as a therapeutic tool for people with amnesia.

Odour is often linked to the recall of emotional memories, he explains. Since the sense of smell plays a powerful role in human perceptual experiences, Yu hopes their VR technology has potential to help amnesiacs recall lost memories.

When the time and the product are right, Yu is confident he works at the right place to take it to market. “The support from CityU could greatly accelerate the commercialization process, and extensively shrink the required time,” he says.

Cutting-edge lab facilities also help in bringing futuristic tech to the market. For Chan, the SKLTMW has provided “outstanding measurement facilities,” he says. A reconfigurable robotic arm system for instance can precisely and safely measure radiation from devices.

“These university-provided resources have enabled us to conduct prompt testing of our ideas, often leading to unexpected and valuable results,” Chan says.