Fast Thermal Actuators for Soft Robotics

Abstract We present extensions to ChainQueen, an open source, fully differentiable material point method simulator for soft robotics. Previous work established ChainQueen as a powerful tool for inference, control, and co-design for soft robotics. We detail enhancements to ChainQueen, allowing for more efficient simulation and optimization and expressive co-optimization over material properties and geometric parameters. We package our simulator extensions in an easy-to-use, modular application programming interface (API) with predefined observation models, controllers, actuators, optimizers, and geometric processing tools, making it simple to prototype complex experiments in 50 lines or fewer. We demonstrate the power of our simulator extensions in over nine simulated experiments.

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Controlled Fabrication of Quality ZnO NWs/CNTs and ZnO NWs/Gr Heterostructures via Direct Two-Step CVD Method

Nanomaterials ◽

10.3390/nano11071836 ◽

2021 ◽

Vol 11 (7) ◽

pp. 1836

Author(s):

Nicholas Schaper ◽

Dheyaa Alameri ◽

Yoosuk Kim ◽

Brian Thomas ◽

Keith McCormack ◽

...

Keyword(s):

Direct Synthesis ◽

Chemical Vapor ◽

Single Walled Carbon Nanotubes ◽

Materials Synthesis ◽

Oxide Nanowires ◽

Cvd Method ◽

Thermal Actuators ◽

Potential Applications ◽

Walled Carbon Nanotubes ◽

Scalable Production

A novel and advanced approach of growing zinc oxide nanowires (ZnO NWs) directly on single-walled carbon nanotubes (SWCNTs) and graphene (Gr) surfaces has been demonstrated through the successful formation of 1D–1D and 1D–2D heterostructure interfaces. The direct two-step chemical vapor deposition (CVD) method was utilized to ensure high-quality materials’ synthesis and scalable production of different architectures. Iron-based universal compound molecular ink was used as a catalyst in both processes (a) to form a monolayer of horizontally defined networks of SWCNTs interfaced with vertically oriented ZnO NWs and (b) to grow densely packed ZnO NWs directly on a graphene surface. We show here that our universal compound molecular ink is efficient and selective in the direct synthesis of ZnO NWs/CNTs and ZnO NWs/Gr heterostructures. Heterostructures were also selectively patterned through different fabrication techniques and grown in predefined locations, demonstrating an ability to control materials’ placement and morphology. Several characterization tools were employed to interrogate the prepared heterostructures. ZnO NWs were shown to grow uniformly over the network of SWCNTs, and much denser packed vertically oriented ZnO NWs were produced on graphene thin films. Such heterostructures can be used widely in many potential applications, such as photocatalysts, supercapacitors, solar cells, piezoelectric or thermal actuators, as well as chemical or biological sensors.

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Artificial Cutaneous Sensing of Object Slippage using Soft Robotics with Closed‐Loop Feedback Process

Small Science ◽

10.1002/smsc.202100002 ◽

2021 ◽

pp. 2100002

Author(s):

Tomohito Sekine ◽

Yi-Fei Wang ◽

Jinseo Hong ◽

Yasunori Takeda ◽

Reo Miura ◽

...

Keyword(s):

Closed Loop ◽

Soft Robotics ◽

Feedback Process ◽

Loop Feedback ◽

Closed Loop Feedback

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A Soft Resistive Sensor with a Semicircular Cross-Sectional Channel for Soft Cardiac Catheter Ablation

Sensors ◽

10.3390/s21124130 ◽

2021 ◽

Vol 21 (12) ◽

pp. 4130

Author(s):

Eric Rasmussen ◽

Daniel Guo ◽

Vybhav Murthy ◽

Rachit Mishra ◽

Cameron Riviere ◽

...

Keyword(s):

Catheter Ablation ◽

Liquid Metal ◽

Force Feedback ◽

Applied Force ◽

Medical Community ◽

Soft Robotics ◽

Soft Sensors ◽

Cross Sectional ◽

Cardiac Catheter ◽

Specific Loading

The field of soft robotics has attracted the interest of the medical community due to the ability of soft elastic materials to traverse the abnormal environment of the human body. However, sensing in soft robotics has been challenging due to the sensitivity of soft sensors to various loading conditions and the nonlinear signal responses that can arise under extreme loads. Ideally, soft sensors should provide a linear response under a specific loading condition and provide a different response for other loading directions. With these specifications in mind, our team created a soft elastomeric sensor designed to provide force feedback during cardiac catheter ablation surgery. Analytical and computational methods were explored to define a relationship between resistance and applied force for a semicircular, liquid metal filled channel in the soft elastomeric sensor. Pouillet’s Law is utilized to calculate the resistance based on the change in cross-sectional area resulting from various applied pressures. FEA simulations were created to simulate the deformation of the sensor under various loads. To confirm the validity of these simulations, the elastomer was modeled as a neo-Hookean material and the liquid metal was modeled as an incompressible fluid with negligible shear modulus under uniaxial compression. Results show a linearly proportional relationship between the resistance of the sensor and the application of a uniaxial force. Altering the direction of applied force results in a quadratic relationship between total resistance and the magnitude of force.

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Analysis of thermo-mechanical coupling damage behavior in long-term performance of microelectromechanical systems actuators

International Journal of Damage Mechanics ◽

10.1177/10567895211033972 ◽

2021 ◽

pp. 105678952110339

Author(s):

Jiaxing Cheng ◽

Zhaoxia Li

Keyword(s):

Damage Mechanics ◽

Microelectromechanical Systems ◽

Mechanical Performance ◽

Damage Model ◽

Irreversible Damage ◽

Damage Behavior ◽

Thermal Actuators ◽

Long Term Performance ◽

Term Performance

Effective numerical analysis is significant for the optimal design and reliability evaluation of MEMS, but the complexity of multi-physical field couplings and irreversible damage accumulation in long-term performance make the analysis difficult. In the present paper, the continuum damage mechanics method is used to develop a creep damage model and conduct long-term performance analysis for MEMS thermal actuators with coupled thermo-mechanical damage behavior. The developed damage model can make a connection between the material deterioration due to microstructure changes and the macroscopic responses (the change of thermo-mechanical performance or structure failure). The numerical simulations of coupled thermo-mechanical behavior in long-term performance are implemented using the finite element method, which is validated through comparison with previous literature. The numerical results demonstrate that the proposed damage model and numerical method can provide effective assessment in the long-term performance of MEMS thermal actuators.

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