Rotary Inchworm Motor for Underwater Microrobot Propulsion

Mauricio Bustamante Eguiguren

EECS Department
University of California, Berkeley
Technical Report No. UCB/EECS-2024-182
August 18, 2024

http://www2.eecs.berkeley.edu/Pubs/TechRpts/2024/EECS-2024-182.pdf

Swimming microrobots have significant potential for biomedical applications and distributed sensing. To date, most work has relied on external fields for control control. To achieve au- tonomy, locally controllable propulsion mechanisms must be developed. This thesis presents an rotary inchworm motor designed to drive an artificial flagellum, inspired by bacterial flagellar motors found in nature. The design adapts electrostatic gap closing actuators with angled arms for rotational motion. The devices are fabricated in an SOI process with a bonded lid featuring through-wafer vias as a mechanical feedthrough for the flagellum. A hydrophobic coating is applied to prevent water ingress through small gaps, thus keeping the gap closing actuators dry. This process also provides an additional layer of routing for reduced complexity. Motors with rotation rates up to 633 rpm at actuation frequencies of 1.7 kHz are demonstrated to operate reliably in dry conditions. Additionally, promising electrical and optical results are presented, preventing water ingress to gap-closing actuators at low pressures. Effective operation of the mechanism underwater remains a challenge.

Advisor: Kristofer Pister and Michel Maharbiz

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BibTeX citation:

@phdthesis{Bustamante Eguiguren:EECS-2024-182,
    Author = {Bustamante Eguiguren, Mauricio},
    Title = {Rotary Inchworm Motor for Underwater Microrobot Propulsion},
    School = {EECS Department, University of California, Berkeley},
    Year = {2024},
    Month = {Aug},
    URL = {http://www2.eecs.berkeley.edu/Pubs/TechRpts/2024/EECS-2024-182.html},
    Number = {UCB/EECS-2024-182},
    Abstract = {Swimming microrobots have significant potential for biomedical applications and distributed sensing. To date, most work has relied on external fields for control control. To achieve au- tonomy, locally controllable propulsion mechanisms must be developed. This thesis presents an rotary inchworm motor designed to drive an artificial flagellum, inspired by bacterial flagellar motors found in nature. The design adapts electrostatic gap closing actuators with angled arms for rotational motion. The devices are fabricated in an SOI process with a bonded lid featuring through-wafer vias as a mechanical feedthrough for the flagellum. A hydrophobic coating is applied to prevent water ingress through small gaps, thus keeping the gap closing actuators dry. This process also provides an additional layer of routing for reduced complexity. Motors with rotation rates up to 633 rpm at actuation frequencies of 1.7 kHz are demonstrated to operate reliably in dry conditions. Additionally, promising electrical and optical results are presented, preventing water ingress to gap-closing actuators at low pressures. Effective operation of the mechanism underwater remains a challenge.}
}

EndNote citation:

%0 Thesis
%A Bustamante Eguiguren, Mauricio
%T Rotary Inchworm Motor for Underwater Microrobot Propulsion
%I EECS Department, University of California, Berkeley
%D 2024
%8 August 18
%@ UCB/EECS-2024-182
%U http://www2.eecs.berkeley.edu/Pubs/TechRpts/2024/EECS-2024-182.html
%F Bustamante Eguiguren:EECS-2024-182