Tactile sensation in prosthetic fingers
One of the many amazing features of the human hand is tactile sense, something that has proven a challenge to reproduce in prosthetic hands. The ability to ‘feel’ an object in the hand is a good start, but the next step may be distinguishing texture. This was an initial study exploring possible tactile stimulation, using non-amputees initially. The results showed that tactile cues can be elicited by these methods, and further research is needed into the application in and prosthetics to allow this feature for amputees.
The first approach was use of mechano-neiro-transduction (MNT) processes aimed at mimicking the natural coding, teamed with tactile sensors in a robot finger. The process was tested by use of needle microelectrodes stimulating the peripheral nerve fibres relevant to the palmar surface of 4 fingers of the subject’s hand. connected to the robot hand. The researchers were careful to limit interference by removing visual or acoustic cues. Outcomes where compared to stimulation of the real hand and a strong correlation was found.
This was then modelled to translate to use in Transverse Intrafascicular Multichannel Electrodes for use in transradial amputees, discrimination of textures using this method was found to be high than MNT, if a slow sliding velocity is used. However, for complex textures the system is not so well adapted. Further, this was a limited study on a small number of individuals and further experimentation is necessary.
Why is human touch so important? You can find an interesting article to read deeper into this subject here!
> From: Oddo et al., Elife 5 (2016) e09148(Epub ahead of print). All rights reserved to The Author(s). Click here for the Pubmed summary.