Robotic Touch: Artificial skin brings robots closer to ‘touching’ human lives

When we anticipate the different future innovative technologies we imagine that the manufacturing industry will be completely automated, routine medical procedures will be robot-assisted and the world’s most puzzling crimes will be unraveled by robotic-detectives. It’s fair to say that robots have made significant developmental strides since their inception into our society. 

Image credit: Pete Linforth via Pixabay

Although robotic process automation has increased the efficiency of manual tasks across the globe, ethicists still argue that they lack certain ‘human’ attributes. This rationale allows us to maintain a framework where humans remain superior despite increasing advances in robotics. One trait that is uniquely human is our ability to detect environmental stimuli and elicit a neurological response. Somatosensation allows us to perceive sensory stimuli coming from our skin. It is the force at play when our brain accumulates information about our natural environment and perceives potential danger. The rising demand for more advanced soft robotic systems has led to the development of artificial skin that enables robots to experience and interpret sensory stimuli in a similar manner to humans. 

Somatosensation allows us to perceive sensory stimuli coming from our skin. It is the force at play when our brain accumulates information about our natural environment and perceives potential danger.

Significant attempts have been made to integrate tactile sensing capabilities into robotic systems. Enhancing robotic sensual abilities could expand the soft robotic practical applications, revolutionizing both healthcare and synthetic biology. A myriad of research groups worldwide are striving towards the creation of robotic skin with many creating successful prototypes. Significant advancements were made in 2019 by a group at the Technical University of Munich via the creation of artificial skin that can detect contact, spatial proximity and temperature.  

Researchers are welcoming a new era of haptic technology with novel tactile sensors that can accurately measure touch, force and vibration. The most progressive advance in the field has come from researchers in Japan that have constructed 3D vision-guided artificial skin which they’ve named TacLINK. TacLINK can gather tactile information via the use of a stereo 3D digicam and a finite factor model-based evaluation system. This vision-guided technology confers many advantages as it enables high power tactile sensing. Innovation in this field marks a triumph in biorobotics as the high-density of mechanosensors involved in human proprioception make it extremely difficult to replicate natural skin.

The primary motivation driving the development of TacLINK was the desire to enhance the safety of human-robot interactions in alignment with increasing reliance on the secondary and tertiary sectors on automated work tasks. Robot attributes like size, strength and capability must grow alongside the tools used in human environments. Despite these technological advancements, societal acceptance of human-like robots will be controversial. Mori’s ‘Theory of Uncanny Valley’ is an interesting concept proposed by Maahiro Mori in the 1970’s which suggests that as robots become more human-like, they become more appealing up to a certain extent. As robots become too human-like, our affinity for them decreases as we experience feelings of unfamiliarity and strangeness – we descend into a valley of fear and unfamiliarity. Human mechanosensation is a wonderful phenomenon that is the basis of our sense and touch but interacting with non-living life forms that have this level of perception could result in societal rejection of this artificially programmed technology. 

As robots become too human-like, our affinity for them decreases as we experience feelings of unfamiliarity and strangeness – we descend into a valley of fear and unfamiliarity.

Arguments concerning the ethical nature of robotic skin can be counteracted by the potential benefits it may have in medical technology and bioengineering. The emulation of human skin in prosthetics has revolutionised medical treatment post-amputation. The development of pain-sensing electronic artificial skin enables a prosthetic arm user to sense danger through a feedback system engineered in the artificial mechanosensory network. Last year, a research group from the University of Melbourne developed an innovative electronic skin system for temperature detection via the utilization of vanadium oxide; an extremely temperature-sensitive material that can change its electronic behaviour when temperatures surpass a pre-programmed threshold. This electronic change triggers electrical signals that mimic those generated by biological thermoreceptors. This electrical signal is relayed to a brain-mimicking circuit which processes inputs from the electrical circuit and produces a response output based on mathematical threshold values. The aim of this electric circuit design was to create a motor response feedback system that mimics biological motor outputs.

It is not just the ethics of robotic skin that should concern us but their sustainability too. The scaling and operation of large numbers of mechanosensors and readout electronics could pose an issue when energy consumption becomes unsustainable. Researchers at the University of Glasgow are innovating new technologies to overcome energy-related issues by utilising solar energy to create the world’s first tactile sensing electronic skin. This electronic skin structure is energy autonomous – made from a graphene-based layer of touch sensors displayed on solar cells. The cells generate sufficient energy for the powering of micro-actuators that control hand movement. These micro-actuators can also create a unique sense of touch by measuring different variations of solar cell output. This system has generated a sustainable solar-powered skin that can deduce object proximity and location. 

Slowly, the world of soft robotics is evolving. TacLINK has evoked a new area of haptic technology where algorithms can decode information from images of 3D artificial skin. The issues of biorobotic-related scalability and sustainability have been addressed by the design of solar-powered tactile sensing skin. Innovations like these are an exciting snippet of what lies ahead as biorobotics transcends boundaries once thought impossible. Future developments in artificial skin engineering will enable insurmountable advances in healthcare. From a practical perspective, endowing robots with a unique sense of touch will unveil numerous possibilities for artificial intelligence and its applications. Mundane tasks could open up to new levels of automation and tactile sensing could allow robots to interact with humans on an emotional level. 

Written by Eva Guinane and edited by Shona Richardson

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