Our hearing, vision, smell, taste and touch are under constant threat from stimuli, routines, and ailments but bio-engineering, nanotechnology, electronics, neuroscience and biofabrication have enabled many breakthroughs. Every breakthrough opens the door to new possibilities but there is much more to be done. The number of sensory-deprived patients globally is expected to increase, so continued R&D and ‘nextgen’ bionics solutions are highly desirable. Fortunately, more bionic innovations and devices are emerging, only some of which are touched upon here.
The Cochlear implant, Australia’s first moon-shot discovery in bionics, has seen significant enhancements in functionality and aesthetics since its invention 50 years ago. It allowed a man who had been profoundly deaf for 17 years to hear again. 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 more people world-wide.
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 Collette Mackay’s EarGenie™ for personalised management of hearing impairment uses several measures of neural activity including 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.
Looking at other human senses, Bionic Vision Australia is restoring sight to individuals undergoing trials with the aid of a prototype bionic vision implant system. The device implanted in the rear of the eye (the retina) has initially given light perception and a sense of vision to individuals with degenerative retinal conditions. However, other innovations to improve eye sight are also emerging. Scientists at the University of California recently created a contact lens controlled by eye movements (a soft biomimetic lens that responds directly to electric impulses, with the lens changing its focal length depending on the signals generated). The researchers involved say the innovation could lead to “visual prostheses, adjustable glasses and remotely operated robotics in future.
Perhaps the most invasive bionic vision solution is the Argus II from Second Sight that is also primarily used by those who have advanced retinitis pigmentosa. The Argus II allows people to discern objects with high contrast. Another option, the Prima from Pixium (a subretinal device) is similar to the Argus II with more electrodes. The Pulse2 Percept from University of Washington, an open source simulation framework, allows researchers to model what a blind person sees when a prosthetic is switched on.
Visual neurobionics devices are now commercially available and include the Alpha IMS System from Retina Implant (a sub-retinal device). This device employs a 1500 electrode microchip which is wireless, and it has the advantage of drawing on natural eye movement. Another sub-retinal prosthesis from Second Sight, the Orion, is also wireless and is used to treat a wide range of conditions that affect human vision.
A separate suite of devices like the Aria from Google Glass (a non-corporeal aide) provides navigation and a description of immediate surroundings as does the Cara from Microsoft HoloLens, an augmented reality headset that acts as a navigator and assigns customised tonal and spatial voices to objects in the immediate field of vision. Looking ahead, significant developments in Stem Cell Technology are expected to lead to new vision treatments but difficulties can arise in delivering these cells to the retina.
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.
Future haptic wearables could go further to incorporate behavioural, physiological and cognitive states. Adelaide-based neuroscientist Dr Kerr says “we need to better understand the proven benefits of human touch, eye gaze, voice and sharing physical space with other people. When we interact through eye or skin contact, speaking or sharing physical space, we synchronize with each other electrochemically. Nowadays, it is possible to measure the numerous benefits that this interaction brings e.g. increased neuroplasticity in our brains and improvements in our immune health. It also delivers increased trust and empathy and improves our complex problem-solving capabilities. Many of these physiological effects don’t occur at all when humans interact with technology”.
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).
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.
In a world that is becoming multisensory in every way, interest in the mechanisms that underpin multisensory perception is growing. Researchers are particularly interested in the brain’s ability to integrate information coming simultaneously from different senses e.g. the brain’s ability to interpret sound even if the signal reaches the areas of the brain dedicated to image processing. Devices that extend ‘sensory cross-talk’ are also being explored e.g. blind people who describe seeing ‘around’ themselves using sound. Research among blind people has also stimulated the skin of the back in response to the output of a forward facing camera (sensations on the back are translated into an impression of what is in front of them through the brain’s learning process).
Building on the electrodes included in the bionic ear, many more sensory prostheses will be available in future. Limiting factors so far have been the ability to produce devices with multiple electrodes which can be shielded from each other so they can be stimulated with specificity, movement of some body parts, wet bodily environments, and other factors such as the ability to charge devices internally implanted in the human body. However great strides have been made in the area of bionics senses, and will continue to be made in the coming decade.
Winners of the Bionic Senses Challenge will deliver a ‘nextgen’ innovation with practical benefits for health consumers in one of the following areas:
Bionic ear / neuromodulation devices and technologies designed to overcome hearing and/or auditory processing disorders, improve the perception of speech or repair the inner ear
Bionic eye / vision devices and technologies that address genetic or acquired vision disorders
Bionic devices, products or technologies that help to restore a sense of touch, taste, smell, orientation or balance
Bionic devices and technologies that deliver multi-sensory treatments or experiences e.g. a connection to the IOT and use of AI and VR/AR to enhance outcomes
Innovative health services and programs that optimise the benefits of human to human interaction alongside human-technology interfaces to accelerate healing and wellbeing