Wearable multiplexed biomedical electrodes

Project Information

WEARPLEX

Grant agreement ID: 825339

DOI

10.3030/825339

Project closed

EC signature date 12 November 2018

Start date 1 January 2019

End date 28 February 2022

Funded under

• INDUSTRIAL LEADERSHIP - Leadership in enabling and industrial technologies - Information and Communication Technologies (ICT)

Total cost

€ 3 732 748,75

EU contribution

€ 3 732 748,75

Coordinated by

UNIVERSITY OF SOUTHAMPTON
United Kingdom

Periodic Reporting for period 2 - WEARPLEX (Wearable multiplexed biomedical electrodes)

Reporting period: 2020-09-01 to 2022-02-28

Summary of the context and overall objectives of the project

WEARPLEX is a multidisciplinary research and innovation action with the overall aim to integrate printed electronics with flexible and wearable textile-based biomedical multi-pad electrodes. It aims to answer the growing need for user friendly electrodes for pervasive measurement of electrophysiological signals and application of electrical stimulation. It focused on the development of the printable electronics and manufacturing processes for textile based multi-pad electrodes with integrated logic circuits that enable a significant increase in the number of electrode pads (channels) with the same number of control wires and facilitate the creation of new products in the sectors of medical electronics and life-style.

The advanced printed electronics integrated in WEARPLEX electrodes allows the individual pads to be connected in arbitrary configurations to the output leads of the electrode. Therefore, the pads can be flexibly organized into virtual electrodes of arbitrary position, shape and size that can be connected to standard multi-channel recording and stimulation systems. In addition, software methods have been developed for automatic calibration of these electrodes, to detect stimulation/recording hotspots and adjust the electrode pad selection accordingly. Therefore, the WEARPLEX project results will lead to a new generation of smart electrodes that will be able to adapt simultaneously to the user (wearable and stretchable garment), recording/stimulation scenario (movement type and target muscles) and recording/stimulation system (number of channels). This is a paradigm shift in designing the recording and stimulation systems, as the switching electronics is shifted from the custom-made stimulator/recording device to the smart electrode, leading to a universal solution compatible with any system.

19 peer reviewed papers have been published during the project, with 10 conference talks, 3 workshops, 1 webinar and 1 magazine article. 5 main demonstrators have been produced and videos of these in operation can be found on the project website links to YouTube.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The key results from period 1 were:
- The WEARPLEX concept has been fully specified in Alpha and Beta prototypes.
- Alpha prototypes for EMG and FES electrode systems printed on PET and fabric have been demonstrated to the scientific community.
- Simulation models for the printed transistors and skin/electrode interface have been developed.
- Optimal materials for all the printed layers have been identified.
- Significant reduction in the size of the stimulation and control unit.
- Identification of the best compromise for flexible but smooth printing on fabric.
- Roll to roll fabrication equipment suitable for manufacturing WEARPLEX electrodes tested.


The key results from period 2 were:
- The WEARPLEX Beta and Gamma demonstrators were fully specified, with feedback from an Advisory board of industry experts.
- Beta and Gamma prototypes for EMG and FES/TENS electrode systems printed on PET and fabric have been demonstrated to the scientific community.
- Simulation models for the printed transistors and skin/electrode interface have been further developed.
- Gamma wearable stimulation and recording electronics has been successfully adapted (GPIOs voltage, stimulation voltage, GPIOs command protocols) to match the very latest OECTs shift register and decoder requirements.
- Identification of the best compromise for flexible but smooth printing on fabric and fabric for sleeve construction.
- Roll to roll and sheet to sheet fabrication equipment suitable for manufacturing WEARPLEX electrodes and OECT circuits demonstrated.
- Successful validation of Beta and Gamma electrode prototypes for electrical stimulation (ES) and EMG recording
- New rGO water- (green solvent-) and solvent-based screen-printable inks developed and some of them proved to be biocompatible.
- Optimal ink selection for Gamma prototypes for each layer identified and their biocompatibility confirmed via cytotoxicity and irritational trials; providing a range of suitable inks to be used in future applications that are safe for human contact applications.
- Printable versions (Beta and Gamma) of HMEC developed and used for FES electrode testing and electrode/skin interface model improvements.
- Passive EMG sleeve electrodes developed and characterized using electrical, physical and online control tests (pattern classification and regression).
- OECT components and complete gamma electrode solutions printed and switching function successfully demonstrated for EMG recording and electrical stimulation.
- Recording and stimulation electronics and human model equivalent circuit adapted for use with Gamma prototypes.
- 12 journal publications, 5 conference/webinar presentations and 2 workshops held in Period 2.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The WEARPLEX electrode system will allow the stimulation of muscles and recording of their activity from the same wearable device. The system has been integrated into a textile to make it comfortable to wear, easy to set up and allow it to be used over a prolonged period.

The WEARPLEX electrode will allow users and clinicians to produce data outputs suitable for use in a number of applications; from rehabilitation to leisure activities.

Developments for the OECT printed transistor circuitry, printed fabric/electronics interface, printed rGO ink development and Human Model Equivalent circuit to allow electrode testing without human risk have all led to peer reviewed journal and conference publications showing progress beyond the state of the art. WEARPLEX has produced 12 journal and 5 conference presentations across the printed electronic, e-textiles and healthcare research fields during Period 2.

Additional developments on the EMG/FES selection algorithms, printed electrode structures, durability of printed e-textiles and efficacy of skin/electrode interface materials are the subject of papers currently in progress and will be further examples of the state of the art developments driven by the WEARPLEX project.

The level of control on the stimulation area and intensity, and the recording sensitivity offered by the full WEARPLEX system represents a paradigm shift in capabilities for both these fields individually and in gesture control and rehabilitation when combined.

In particular, the OECT developments have produced the most complex circuitry ever achieved using this architecture, the 3-8 decoder and 8-bit shift register – with 38 and 156 OECT transistors respectively per circuit. For the electrode algorithm, a high performance gesture classification in realistic conditions has been demonstrated using only 8 electrodes from a set of 48 when placed strategically for each subject; a particular strength of the WEARPLEX multi-pad approach.

Due to the COVID related restrictions on large events, the developed Beta and Gamma prototypes were demonstrated via two online webinars to the various communities targeted by WEARPLEX.

WEARPLEX Human Model Equivalent Circuit design stages

WEARPLEX OECT circuits printed on to textile

WEARPLEX gamma electrode for recording

WEARPLEX alpha phase recording electrode

WEARPLEX gamma stimulation electrode