Controllably Biodegradable Conductors for Robotic Tactile Skins

Project Information

BioConTact

Grant agreement ID: 101022279

DOI

10.3030/101022279

Project closed

EC signature date 5 March 2021

Start date 1 April 2022

End date 31 March 2024

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 171 473,28

EU contribution

€ 171 473,28

Coordinated by

FONDAZIONE ISTITUTO ITALIANO DI TECNOLOGIA
Italy

Periodic Reporting for period 1 - BioConTact (Controllably Biodegradable Conductors for Robotic Tactile Skins)

Reporting period: 2022-04-01 to 2024-03-31

Summary of the context and overall objectives of the project

Consumer electronics, such as laptops, smartphones, and flat-screen TVs, are widespread in European society, representing a significant business sector with numerous companies and millions of users. However, issues like scarcity, toxicity, short lifespans, and recycling complexity necessitate a shift towards more sustainable and easily disposable materials for electronics. E-waste management has become a pressing concern for national governments due to the growing stockpile, expected to reach 120 million metric tons annually by 2050, fueled by the proliferation of flexible devices and the Internet of Things. Additionally, the increasing ubiquity of robotics, crucial for Europe's prosperity, adds to the e-waste issue, particularly with humanoid robots constructed from non-biodegradable materials. Transitioning to sustainable alternatives, including tactile-sensitive biodegradable skins, represents a pivotal shift towards environmentally friendly technologies in electronics and robotics.

This initiative is important for society as it fosters the convergence of green robotics and electronics, bolstering Europe's leadership in these domains. The project influence various research areas, including plastic/bioplastic and biocomposite development, while exploring alternative end-of-life solutions such as biodegradation in seawater for materials for electronics. BioConTact aims to reduce e-waste, enhance the long-term sustainability of both sectors, mitigate pollution, and align with the UN's Sustainable Development Goals (SDG9 and SDG12).

The objectives of BioConTact are to create flexible electrical conductors with controllable biodegradation for applications requiring long-term stability, including human mimicking biodegradable skin for robotics. Specific goals include:
1. Develop flexible conductors with controllable degradation by formulating conductive inks using biodegradable polymers and transient metals and functionalize degradable substrates via a scalable spray-coating process. These conductors will show a tunable biodegradation in environmental conditions based on material formulations.
2. Produce biodegradable sensors, such as capacitive or piezoresistive sensors.
3. Design skins using various conductor-biopolymer combinations, optimizing their performance for applications like humanoid robotic hands.

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

Developing conductive inks using transient metals and biopolymers that, after coating, showed stable and low sheet resistance was challenging. Initial attempts with different metallic microparticles and biopolymers resulted in unstable, non-conductive coatings due to the passivation layer on the metallic particles. Only one material formulation achieved the desired conductivity and stability. Attempts to replicate success with other combinations resulted in unacceptably high sheet resistance. In parallel, alternative inks using vitrimer (V-Inks) and PBAT (PBAT-Inks) binders with carbon nanomaterials were created, demonstrating promising applications in robotic skins and tactile sensors. These inks exhibited excellent piezoresistive responses, self-healing capabilities, and biodegradability.

BioConTact successfully developed a conductive ink using a transient metal and a biopolymer binder, achieving the target sheet resistance on various substrates. While initial attempts at plasticization were unsuccessful, further testing with another plasticizer is planned. Efforts are ongoing to create biodegradable plane capacitors with these inks and are being engineered to develop tactile sensors for robot hands. On the other hand, V-Inks and PBAT-Inks were successfully integrated into robotic components like SoftHand3 and MOCA, an industrial robot, showing promising results and enhancing functionalities such as impact monitoring and manipulation guidance for visually impaired individuals.

BioConTact established a solid online presence with a dedicated website and social media profile. The Researcher participated in four international conferences, delivered six talks, and provided several invited lectures at prestigious institutions. Public engagement included presentations at the PhD students' welcome day at IIT and active sharing of research findings on various social networks and online platforms, promoting the project's advancements in sustainable materials for electronics and robotics.

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 progress beyond the state of the art reached during BioConTact can be schematized as follows:

1) The first ink was made of transient metals, a biopolymer binder, and a green solvent. The ink obtained was coated on several substrates and was characterized in terms of sheet resistance, obtaining values < 10 Ω/sq. Biological oxygen demand tests are ongoing.
2) The first biobased and biodegradable vitrimer-based ink (V-ink) was made using epoxidized soybean oil and a boronic ester crosslinker as a binder into water and ethanol and adding graphene nanoplatelets (GnPs) and carbon nanofibers (CnFs) as conductive fillers. Such ink, sprayed on natural rubber substrates, proved suitable for detecting repeated strain release cycles and was engineered as robotic skin for SoftHand3, showing promising results. This skin can self-heal after damage and has a tuneable degradation rate based on conductive filler loading. Additionally, it is chemically recyclable, allowing the conductive layer to be redissolved and reapplied.
3) The first conductive ink was realized of anisole, a soft polybutylene adipate terephthalate (PBAT) biodegradable binder, and CnFs (PBAT-Ink). It was used to functionalize a cotton t-shirt with components like a solar-powered vibrotactile device for visually impaired people. It was employed in industrial robots for piezocapacitive feedback to monitor impacts.

The expected results to end the project are the engineerization of the ink in 1) to realize fully degradable capacitive tactile sensors for robotics hands.

The potential socioeconomic impact of BioConTact is towards reducing and simplifying certain classes of waste coming from the electronic sector and realizing sensors that are fully degradable and will not accumulate in the environment or landfills.
BioConTact will reduce e-waste, enhancing the sustainability of the robotics sector.
This initiative foster sustainable robot materials, establishing the PI as a global leader in the field.
BioConTact's success significantly impact the synergy between green robotics and electronics.
BioConTact aligns with the UN's sustainable development goals (SDG9 and SDG12).

General Idea of BioConTact