Investigation of biological seal whiskers to create artificial whisker sensors for underwater robots

Project Information

SEALSENSE

Grant agreement ID: 101042370

DOI

10.3030/101042370

EC signature date 1 April 2022

Start date 1 September 2022

End date 31 August 2027

Funded under

• European Research Council (ERC)

Total cost

€ 1 469 913,75

EU contribution

€ 1 469 913,75

Coordinated by

RIJKSUNIVERSITEIT GRONINGEN
Netherlands

Periodic Reporting for period 1 - SEALSENSE (Investigation of biological seal whiskers to create artificial whisker sensors for underwater robots)

Reporting period: 2022-09-01 to 2025-02-28

Summary of the context and overall objectives of the project

The fundamental research question addressed by the ERC Starting Grant Project SEALSENSE is to investigate and understand the crucial role played by whiskers in seals in enabling fish trail tracking with remarkable accuracy. The project aims to conduct experimental investigations of real seal whiskers (from Harbor seals and grey seals) deployed in flows to understand the vortex-induced vibration suppression behaviour of the whiskers. Ultimately, the project also proposes the demonstration of underwater navigation of robotic vehicles that use whisker-inspired MEMS sensors to attain artificial vision allowing them to manoeuvre in dark and turbid water conditions.

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 aims of the SEALSENSE project have been classified into 3 work packages (WP) and each WP is further sub-classified into tasks.
WP1: WP1 focuses on the biological inspiration, the seal whiskers. We have conducted thorough morphological, mechanical and material characterization of seal whiskers of harbor seals (phoca vitulina) and grey seals (Halichoerus grypus). We have also conducted fluid–structure interaction studies and experimental investigations involving a whisker array mounted on 3D-printed microelectromechanical systems sensors, the vibration characteristics of the whisker array and the interaction between neighbouring whiskers in steady flows and fish-wake-like vortices were explained for the first time.
WP2: This WP targets the development of whisker-inspired MEMS sensors that allow quantification of the long distance wake tracking capability of seal whiskers. We designed and utilized a bioinspired, fully 3D-printed MEMS cantilever sensor incorporating both real and 3D-printed seal whiskers. A high-gauge-factor graphene nanoplatelet piezoresistor, positioned at the proximal end of the MEMS cantilever, measured the vibration frequencies and amplitudes of the whisker structure attached to the distal tip. The MEMS whisker sensor was tested under various experimental conditions that mimic the natural active hunting environment of seal whiskers, providing further insights into their ultrasensitive fish wake-tracking capabilities. The developed 3D-printed MEMS sensor is the first of its kind to exhibit whisker-inspired wake-tracking capabilities. Its compact form factor holds great promise for integration into underwater robots, enhancing environmental perception and enabling long-distance object tracking.

Main Achievements:
Journal publications:
1. Kamat, AM, Zheng, XZ, Bos, J, Cao, M, Triantafyllou, M & Kottapalli, AGP 2024, 'Undulating Seal Whiskers Evolved Optimal Wavelength-to-Diameter Ratio for Efficient Reduction in Vortex-Induced Vibrations', Advanced science , vol. 11, no. 2, 2304304. https://doi.org/10.1002/advs.202304304
2. Zheng, XZ, Kamat, AM, Cao, M & Kottapalli, AGP 2023, 'Wavy Whiskers in Wakes: Explaining the Trail-Tracking Capabilities of Whisker Arrays on Seal Muzzles', Advanced science , vol. 10, no. 2, 202203062. https://doi.org/10.1002/advs.202203062
3. Zheng, XZ, Kamat, AM, Krushynska, A, Cao, M & Kottapalli, AGP 2022, '3D Printed Graphene Piezoresistive Microelectromechanical System Sensors to Explain the Ultrasensitive Wake Tracking of Wavy Seal Whiskers', Advanced Functional Materials, vol. 32, no. 47, 2207274. https://doi.org/10.1002/adfm.202207274

Public engagement activity with stakeholders:
4. ‘Weekend of Science’ a 2 day event (7-8 October 2023 involving seal scientists, veterinarians, students and general public was conducted at the Seal center at Pieterburen, a seal rehabilitation center at the North of Netherlands. This activity involved a talk titled “Wavy whiskers of Wonders” and various hands on demonstrations with 3D printed seal whiskers to general public where people can feel the vibrations of the whiskers the way the seal would experience.

Media reports:
5. ‘Seal whiskers: an example of a perfect technique’ an article featuring my research on seal whiskers was published in Broerstraat 5 Magazine, University of Groningen.

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)

We collaborated with Seal center, Pieterburen, a seal rehabilitation center in the North of the Netherlands, which conducts necroscopy of deceased seals found in the shores of the North sea. Through this collaboration, we were the very few scientists across the globe to get access to all the whiskers on the muzzles of harbor seals and grey seals. This allowed us to conduct morphological studies through microscopy and blue light scanning. While we anticipated that the non-dimensional parameter (λ/Dm) is an important factor that controls the VIV response, we were amazed to realize that this ratio was more or less fixed among all the whiskers not only within the muzzle of a single seal, but was found to be consistently within the range of 4.4-4.6 among harbor seals as well as grey seals. Computational and experimental studies conducted in water flows by employing MEMS sensors at the bases of the whiskers revealed the importance of this optimal evolution in minimizing VIV and maximizing fish wake induced vibrations (WIV). We made the whisker scans, morphometrics, the whisker framework and reconstructed whisker models openly available to the scientific community (see supplementary information, Advanced Science, open access).

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