Background insights

Our hearing, vision, smell, taste and touch are under constant threat from stimuli, routines, and ailments. However, the recent explosion of bio-engineering, nanotechnology, electronics, neuroscience and biofabrication has enabled many breakthroughs.

Every discovery opens the door to new possibilities, and there is much more to be done. With the number of sensory-deprived patients globally set to increase, continued R&D of next-generation bionics solutions are highly desirable. Excitingly, more bionic innovations and devices are emerging, with just some of them touched on here.

Vision

Globally, bionic vision systems are likely to be the next most publicised innovation in the bionic senses domain. Many learnings from Cochlear technologies have influenced bionic vision technologies (with some of the most promising innovations still in development and trial stages).  Bionic eyes in the form of retinal prostheses can be broadly categorised as epi-retinal, sub-retinal and supra-choroidal based on the form of electrical stimulation they employ. Other forms of stimulation are ultrasonic such as those which are photovoltaic or chemical in nature.

The Australian-born Bionic Eye System from Bionic Vision Technology (BVT) currently in development consists of a tiny camera mounted on a pair of glasses which send electrical signals to a wearable processor (a similar configuration to the cochlear implant). Its aim is to create an affordable implant for those who suffer from retinitis pigmentosa. To date, pilot studies have been conducted with implantation and trial of the prototype system in seven patients who are almost totally blind. Clinical studies to date have demonstrated the safety and benefits of the system in obstacle avoidance and object recognition. In 2020, BVT is refining its vision processing algorithms and its plans for market entry.

An entirely different vision solution is sought and needed by people with advanced retinal disease with a loss of neuronal elements, a damaged optic nerve as a result of disease (such as glaucoma), trauma or injury.

Monash Vision Group, a Melbourne-based collaborative partnership between Monash University and Alfred Health, has succeeded in developing a clinically viable alternative with their cortical vision prosthesis known as the Gennaris Bionic Vision System. In a world-first, the Gennaris system bypasses damage to the eye and optic nerve to restore functional vision. The team has already demonstrated the feasibility of a novel fully implantable wireless stimulator (the Gennaris array) in terms of eliciting minimal tissue damage.

Equally exciting is the Phoenix99 Bionic Eye (a joint innovation of University of Sydney and University of New South Wales researchers) which bypasses the retina to ‘trick the human eye into learning to see again’. This system provides an artificial retina via cameras mounted on eyeglasses and an implant placed near the patient’s eyes. A next step for the Phoenix99 team is identifying how to create artificial vision that truly simulates the human eye’s capabilities.

Hearing

The cochlear implant, Australia’s first moon-shot discovery in bionics, has seen significant enhancements in functionality and aesthetics since its invention more than half a century ago. In the words of the Australian inventor of the multichannel cochlear implant, Professor Graeme Clark, the implantation of the bionic ear was the first time that the brain, human consciousness and a replaced human sense had been interfaced. Today a number of different brands exist but the Cochlear Ltd version has helped the most people worldwide.

Early access to hearing is crucial for the development of the brain networks that are involved in language perception and production, but the success of hearing aids and cochlear implants (bionic ears) in small children does vary. Professor Colette McKay’s EarGenie™ for personalised management of hearing impairment uses several measures of neural activity including functional near-infrared spectroscopy (fNIRS) brain imaging, to perform a detailed diagnostic evaluation of a child’s hearing so that an appropriate hearing device can be selected and fine-tuned.

Central auditory prostheses are now available for people with compromised nerves from the cochlear along the pathway to the brain or who have extensive fibrous tissue and/or new bone in the cochlear, or if the cochlear is malformed and the cochlear implant is unable to be used. These are usually implanted in the auditory brain stem, the midbrain or in some studies in the cortex.

Touch

For humans, the ability to experience a normal sense of touch is a high priority, but it is not always possible. If human skin has been damaged or a person is suffering from peripheral neuropathy (numbness or tingling) then restoring a biological sense of touch can be tricky. Likewise, it is a challenge to give prosthetic hands a basic touch-sensing ability, but a lot of progress is being made.

Putting sensors into prosthetic hands can enable a person to change how they hold an object based on how it feels. The sensor in the prosthetic transmits information back to the person’s somatosensory cortex to enable the touch sensation. Haptic wearables can help to overcome sensory impairments related to touch such as slip, texture, temperature, pain, force and other sensations.

Many benefits arise from the human sense of touch including increased neuroplasticity in our brains and improvements in our immune health. Touch also delivers increased trust and empathy and improves our complex problem-solving.

Right now, neurophotonics (the use of optical light in the brain) is very much in focus in R&D designed to deliver a sense of touch. The results sought are the ability to sense different surfaces or objects with a prosthetic hand, to distinguish painful from non-painful sensations and provide sensory feedback in bionic mobility systems

Retaining opportunities for human eye gaze and human touch is vital in healthcare along to build empathic connections between humans (all of which delivers a greater sense of wellbeing).

Without the bonding and trust building that human-to-human interaction brings, users of bionic devices (especially those who have received a device or implant to open up their world) may lose some, if not most of the benefits the device could bring. Retaining opportunities for human eye gaze and human touch is vital in healthcare as is the ability to build empathic connections between humans (all of which delivers a greater sense of wellbeing).

Taste

Far less researched than most other senses is the sense of taste derived from multiple sources which are the gustatory (taste), olfactory (smell) and somatosensory sensations that originate in the mouth at the same time.

Research broadly suggests the insula is the primary taste area which processes the sensory information of taste intensity and quality, but little work has been done in this area. Understanding where cortical activation takes place in response to a taste event is a required platform to treat or overcome pathophysiology related to taste.

Smell​

Depending on the severity of the condition, a sense of taste and smell may return or be relearned, but in the event that this is a more permanent condition. A new sensory system to deliver a bionic sense of smell is on its way. Scientists from Virginia Commonwealth University led by Professor Richard Costanzo have patented an approach to create an array of sensors that would create a ‘smell fingerprint’ and a device that restores damaged olfactory functions.

Potentially, this device will benefit many people who have lost the sense of smell as a result of COVID-19, and the five to 12% of the population who already have this sensory deficit. While further research, testing and clinical trials will take time, strong financial backing from a beneficiary of Professor Costanzo’s device is set to fast-track progress.

Balance

Related to the senses is human balance. The vestibular is responsible for providing our brain with information about motion, head position, and spatial orientation, and is enormously important to the maintenance of our everyday health and wellbeing. Currently, around 1.8 million adults worldwide have severe bilateral vestibular hypofunction.

Assistive devices range from iPad-based medical devices to assist with the diagnosis of vestibular conditions through to Otolith Lab’s non-invasive vestibular system that obtained an FDA Breakthrough Device designation in 2021 and undertook further clinical trials during 2022. For some who suffer from severe vestibular dysfunction or disease, a vestibular implant may be a future pathway.