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Bidirectional Hyper-Connected Neural System

Periodic Reporting for period 3 - EXTEND (Bidirectional Hyper-Connected Neural System)

Reporting period: 2021-01-01 to 2022-06-30

The objective of EXTEND is to develop all the necessary tools to achieve a minimally invasive bidirectional neural interface platform capable of distributed stimulation and recording of neuromuscular activity, for attaining what we refer to as Bidirectional Hyper-connected Neural System (BHNS).

BHNSs can be defined as those systems capable to massively linking and communicating between multiple nerves (or muscles) in the body and multiple external devices. EXTEND will set the foundation for exploring and realizing BHNSs using novel minimally invasive therapeutic interventions that are not possible with current technology. EXTEND project aims at showcasing the feasibility of the BHNS in two scenarios:
(1) Pathological tremor management and suppresion in Parkinson's Disease (PD) and Essential Tremor (ET) patients.
(2) Enhanced interfacing capabilities with external assistive technology in rehabilitation of incomplete Spinal Cord Injured (iSCI) patients by means of Wearable Robotics (WR).

The project will establish a working synergy between six broad and interdisciplinary areas: implantable technology, high-voltage and mixed-signal microelectronics, data processing and analysing, modelling and control, closed loop neuroprosthetics and wearable robotics. At the same time, this work will be framed by an intense discussion on Ethical, Risk Management and Regulatory aspects for the long-term implications of this technology.

The EXTEND concept will result in minimally invasive and implantable peripheral neural interfaces in combination with eTextile-based garments to increase wearability. Being the technology in EXTEND injectable, implantation will be a simple ambulatory procedure (as compared to complex surgical procedures in state-of-the-art technologies) of the electronic implant. It is expected that this will result in affordable technologies and products that support interactions for people with disabilities. In addition, our concept can be seen as a new approach to brain computer interfaces (BCI), in which the distributed recording of the neural code of motion can complement more traditional non-invasive BCI systems both in attaining increased time and space resolution.
The main activities from the beginning of the project (Month 1) to the end of the period covered by the report (Month 54), and main results achieved so far, for each work package were:

Work package 1 (WP1):

- Development of passive miniature circuits for intramuscular stimulation and electromyography (EMG) recording.
- Design and development of the Application Specific Integrated Circuits (ASICs) that enabled the development of ultra-thin and completely injectable versions of the aforementioned devices.
- Design and development of flexible electrodes for experiments that enabled the evaluation of the BHNS concept.
- Design of the external systems for powering the stimulators/sensors and for communicating with them.
- In vitro and in vivo tests to ensure safety and robustness of the flexible electrodes.

Work package 2 (WP2)

- Development, setup and testing of the distributed communication architecture for the BHNS.
- A study on healthy subjects demonstrated the ability of electrical stimulation below the motor threshold to inhibit the voluntary muscular activity of wrist flexors/extensors, which is fundamental for the type of stimulation that can be used with the electrodes produced in EXTEND.
- Development of neural-based models on healthy individuals, containing the development of a subject-specific modelling formulation capable of translating movement neural information into estimates of musculoskeletal kinetic and kinematic function.
- Development of neural-based models for ET, PD and iSCI patients.
- Tremor suppression achieved in ET and PD patients using afferent electrical stimulation (stimulation below the motor threshold) that allowed modulation of spinal reflexes.
- Real-time model-based control of electrical stimulators for tremor reduction.
- Real-time model-based control of lower limb exoskeletons.

Work package 3 (WP3)

- Hospitals involved in the Project analyzed the possible risks for the healthy participants, as well as ET/PD and iSCI patients that participated in the procedures.
- A Data Management Plan was prepared.
- Approvals from the Ethics Committees of the two Hospitals, as well as from the Spanish Agency of Medicines and Medical Devices (AEMPS) were obtained for each of the 3 cycles of experimentation.
- Experiments with healthy participants, as well as with ET/PD and iSCI patients were performed.
- Preliminary BHNS was performed in healthy subjects (cycle 2 of experiments).
- Final BHNS was performed in healthy subjects (cycle 3 of experiments).

Work package 4 (WP4)

- Identification of the non-technological barriers to the adoption of BHNS technology.
- Evaluation and risk management for BHNS technology.
- Policy discourse on human enhancement technologies.
- Preparation of a documentary aiming at connecting the EXTEND with the needs, concerns and informational interests of society. The documentary blended art and science to establish a narration and interpretation of the BHNS technology.

Work package 5 (WP5)

- Project website and social media accounts were set up and were regularly updated.
- A dedicated website for NeuroInterface Hub (open community hub to fully exploit the novel BHNS concept) was set up and information gathering is starting to build up. Promotion of the Hub is ongoing and will be continued.
- Activities for networking and scientific outreach have been done through organizing workshops and participation in conferences.
- Dissemination of project results was done through several papers published in high-impact scientific journals, as well as through talks / presentations in different conferences and summer schools. Active dissemination of the project results has also been done in social media.
- Intellectual property (IP) procedure has been already started: one patent application has been filed in the reporting period (May 2020).
EXTEND will reshape the way neural interfaces are developed, implemented, and used, thus positioning our technology well beyond current state of the art. It will also provoke a wide debate on these technologies, opening channels of discussion between stakeholders to boost and promote future development and collaboration.

EXTEND will go beyond the state of the art in the following areas:
- Bidirectional Neural Interfaces.
- Implanted Micro stimulators and sensors.
- Understanding and managing sensorimotor disorders.
- Ethical, regulation and risk management.
- Competing products, services and patents.

EXTEND outcomes are the following:
- Injectable neuromuscular micro recording/stimulation technology.
- Formulations, algorithms and models of neurophysiological status.
- BHNS system for managing pathological tremors.
- BHNS system for assistive WRs in patients with SCI.
- Analysis of non-technical roadblocks of BHNS technologies.
- The NeuroInterface Hub.

EXTEND main impacts are the following:
- Improved communication and interaction capability of people with disabilities.
- More affordable technologies and products that support interactions for people with disabilities.
- New generation of services that are highly adaptable and customizable to individual contexts.
- New approaches to brain-computer interfaces.