MYKI aims at developing and clinically evaluating a dexterous hand prosthesis which is naturally controlled and perceived by the amputee. This will be possible by overcoming the conventional approaches based on recording electrical signals from the peripheral nervous system (nerves or skeletal muscles) through the development of a radically new Human-Machine Interface (HMI) based on magnetic field principles, both able to decode voluntary motor commands and to convey sensory feedback to the individual. Core of this system is a multitude of magnets implanted in independent muscles and external magnetic readers/drivers (MRDs) able to (i) continuously localize the movements of the magnets and, at specific times, (ii) induce subtle movements in specific magnets. In fact, as a magnet is implanted it will travel with the muscle it is located in, and its localization will provide a direct measure of the contraction/elongation of that muscle, which is voluntarily controlled by the central nervous system. In this way it will be possible to decode the efferent signals sent by the brain by observing a by-product of the muscle fibres recruitment. On the other hand, a movement induced in the implanted magnet by the external MRD, could provide a perceivable stimulus, conveyed to the brain by means of the peripheral sensory receptors present in the muscle (e.g. muscle spindles or Golgi tendon organ) or in the neighbouring skin (tactile mechanoreceptors). In this way we aim to provide tactile and/or proprioceptive sensory information to the brain, thus restoring the physiological sensorimotor control loop. Remarkably, with passive magnetic tags (that do not require to be powered-on) and wearable readers/drivers, it will be possible to implement a wireless, bidirectional HMI with dramatically enhanced capabilities with respect to the state of the art interfaces.
The need/desire for functional replacement of a missing upper limb is an ancient one: historically humans have replaced a missing limb with a prosthesis for cosmetic, vocational, or personal autonomy reasons. In fact the loss of a hand causes severe physical and also mental illness. The inability to grasp and manipulate objects runs parallel with the inability to sense and explore the surrounding world as well as with the inability to use gestures to support speech and express emotions. Still today the restoration, following amputation, of dexterous control equivalent to that of the human hand is one of the major goals in applied neuroscience and bioengineering. To accomplish this requires achieving two important subgoals: the development of a multi-degree of freedom (DoF) artificial hand, and the implementation of an intuitive and effortless human–machine interface (HMI) that maps the sources of volition to the DoFs of the artificial hand, bi-directionally. Although MYKI targets this goal as a whole, is the HMI the primary focus of the project.
The overall objective of the MYKI project is to investigate, design, develop and clinically assess on one selected transradial amputee what we defined MyoKinetic interface, i.e. a magnetic field-based HMI with features beyond the state of the art, for the natural control and perception of a transradial hand prosthesis. This goal will be achieved by addressing the following technological objectives (TOs) and specific scientific objectives (SSOs):
TO1: Localizer of implantable magnets
SSO1: Efferent processing algorithms for MyoKinetic Interface
TO2: Remote actuation of implantable magnets
SSO2: Is it possible to convey physiologically appropriate touch information related to tactile events in the hand prosthesis through implanted magnets?
SSO3: Is it possible to convey physiologically appropriate proprioceptive information of a missing finger or DoF through implanted magnets?
TO3: Smart hand-wrist prosthesis with tactile sensors and shared control
TO4: Biocompatible packaging for implanted magnets
At conclusion of the project, all the foreseen Technological Objectives (TOs) were successfully accomplished. The first volunteer underwent surgery to receive the myokinetic implant on April 1st 2023. Six magnets were implanted in three forearm muscles through a minimally-invasive surgical procedure. Outcomes from the first implant will be available after the explant, set for May 13th 2023.
