Periodic Reporting for period 3 - MYKI (A Bidirectional MyoKinetic Implanted Interface for Natural Control of Artificial Limbs)
Reporting period: 2019-09-01 to 2021-02-28
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
Both the magnets reader and driver (MRD) are at an advanced development stage, being these systems able to, respectively, track or drive up to 4 magnets independently. Online trackers/drivers were developed and tested on different platforms and will be integrated in a closed-loop system the near future.
The IH2 Azzurra robotic hand available at the Scuola Sant'Anna was prepared and made available for pilot sensory feedback studies. Additionally, the artificial hand for the MYKI project was developed exploiting synergies with the EU H2020 DeTOP project (GA #687905). The resulting prototype was also integrated with an advanced sensory system based on strain-gage technologies. In addition, the development of the active wrist is at advanced stage, with few prototypes being currently tested. The team also started studying how humans exchange objects in order to implement in the MYKI prosthesis mechanisms that allow individuals to perceive fluent handover.
In-vitro biocompatibility tests were performed and in-vivo tests are currently ongoing. Both tests aim to identify an appropriate material that can be used as a bio-compatible coating for the magnetic markers. In particular, parylene, titanium, diamond-like carbon and titanium nitride were selected for the tests based on their good bio-compatibility properties emerged from the literature.
Most of this research was submitted for publication on reputable journals and international conferences.
The exciting thing of the MyoKinetic implant is that it will allow natural (or close-to-natural) control – with control we refer to both the efferent and afferent pathways. Indeed, the same pair of magnets implanted in antagonist muscles (e.g. the flexor and extensor pollicis longus), not only will be used to control the physiologically appropriate DoF in the prosthesis (e.g. thumb flexion/extension), but also to evoke proprioceptive feedback through the physiologically appropriate receptors, and to provide physiologically appropriate tactile feedback exploiting biomimetic approaches.
The development of the above mentioned key enabling technologies (TOs and SSOs) will permit MYKI to perform the first in-human implant of the MyoKinetic interface and to assess the proposed control and sensory feedback strategies. Due to its nature the implant is expected to be minimally invasive. Interestingly, although it will be clinically assessed with a transradial amputee (the most prevalent case), it is worth mentioning that the MyoKinetic interface concept adapts nicely to all cases of upper limb amputation (from partial hand amputations, to shoulder disarticulation) and could also find use in lower limb prostheses. Hence, the project could also have a major socioeconomic impact for disabled people in general by providing new interfacing solutions resulting in better quality of life.