Periodic Reporting for period 2 - SOMA (Ultrasound peripheral interface and in-vitro model of human somatosensory system and muscles for motor decoding and restoration of somatic sensations in amputees)
Berichtszeitraum: 2021-09-01 bis 2023-02-28
A 32 element “transducer bracelet” consisting of individual 1 MHz transducers has been developed and used to for recording EMG signals.
Gesture recognition approaches based on EMG signals acquired with ultrasound sensors were developed and tested.
The characteristics of the somatosensory system to be integrated in the prosthetic hand were defined and the bio-inspired somatosensory system for hand prosthesis was developed and tested. The information provided by the sensors has been adopted as input to i) a new force-slippage-temperature control strategy able to guarantee an online reaction of the hand to external stimuli; ii) new encoding algorithms of mechanical, thermal and painful sensations. Encoding techniques for PNS stimulation, neurocomputational models to simulate the CNS response during US stimulation were developed and tested.
Human innervated skin and neuromuscular tissue were developed in vitro using primary human cells. A mechatronic testbed able to produce force, thermal and pain-related stimuli on both the in-vivo and in-vitro models was developed and tested.
Coordination and management were oriented to accomplish the objectives established in the CA.
Both internal and external dissemination activities have been performed.
The SOMA project is advancing the literature thank to the Consortium findings, by means of experiments on animal models, that FUS stimulation cannot activate peripheral nerve axons. Therefore, new innovative solutions have been identified and are under investigation. Existing systems for electrical nerve stimulation are still bulky and not implantable. A fully implantable and wireless solution for electrical nerve stimulation is an incremental novelty with respect to the existing literature. To reduce the invasivity of the stimulation solution, still preserving selectivity, hybrid solutions combining ultrasound and electrical stimulation have been proposed in the literature. They still present technological limits, such as the limited number of stimulating channels, the absence of tunable stimulation parameters. A novel solution that will overcome the aforementioned limits will push beyond the state of the art.
The implementation of a Ultra Fast Ultrasound (UF US) platform capable of identifying single motor unit activity in voluntary contractions has achieved breakthrough novel results. Our method is the first one to combine HD sEMG decomposition and UF US for motor unit identification. With this framework, our experimental data collection and analysis are providing novel insights into muscle contraction and neural control of movements.
The application of B-mode ultrasound for gesture recognition has so far been applied for the classification of different gestures and contractions. Our studies have shown two novelties: i) we used a portable B-mode US system instead of a larger medical grade US; ii) we developed a regression approach, instead of a classification, demonstrating that the US-based regression is superior to the more established sEMG models.
A somatosensory system able to reproduce the human hand physiological characteristics and to replicate the huge variety of sensations felt by humans in the prosthetic system is still missing in the literature.
The information retrieved by a somatosensory system embedded in the prosthesis could be fundamental to ameliorate manipulation performance in several tasks and to restore multimodal somatic sensations, by means of new encoding approaches, with a significant impact on the user’s satisfaction.
The full validation of an artificial innervated skin and muscle biohybrid model based on three different types of stimulation tests (physical, TENS-based and FUS-based) is a novelty that will demonstrate its reliability and the consequent possibility of using it as an artificial testbed as alternative to a living animal.
Our innervated skin represents a unique model in which all components of extracellular matrix are endogenous and not synthetic materials present in the final tissue.