Statement of Objectives

The objective of this project is to create a soft robotic sculpture that reflects the organic response of plants to external stimuli, specifically touch. The sculpture consists of silicone-based parts in the shape of flowers and venus fly traps, which are pneumatically actuated based on capacitive touch sensing. When the parts are touched, the motors activate and fill the silicone flytraps/flowers, creating the illusion of the plant bending inwards, as if closing into the touch. After a few seconds, the parts deflate and return to their original state.

The goals of this project are:

1.  To demonstrate the potential of soft robotics to create organic, lifelike movements that are inspired by nature.
2. To explore the concept of passive response in plants and how it can be applied to robotics.
3. To engage and educate the target audience about the capabilities of soft robotics and the ways in which they can be used in creative applications.

The target audience for this project includes individuals who are interested in robotics, art, and the intersection between the two. This includes artists, engineers, students, and members of the general public who are curious about the possibilities of soft robotics. By showcasing the sculpture in a public setting, the project aims to spark interest and conversation around the topic of soft robotics and its potential to transform our understanding of nature-inspired design.

Reflection

The use of soft robotics technology in the creation of the pneumatic sculpture provided a unique opportunity to explore expressive design and how technology can be used to create organic, lifelike movements. By utilizing silicone-based parts, the sculpture was able to mimic the soft, pliable nature of natural forms, such as flowers and Venus fly traps. The pneumatic actuation allowed for precise and subtle movements, which created an immersive and engaging experience.

The inclusion of the acetate element was primarily for the purpose of adding stiffness and introducing a new material that is somewhere in between hard and soft. The use of capacitive touch sensing to trigger the pneumatic actuation added an interactive element to the sculpture. By responding to touch, the sculpture created a sense of intimacy and connection with the viewer, as the movements of the sculpture were a direct result of the viewer’s actions. This aspect of the sculpture highlighted the potential of soft robotics to create expressive and interactive designs that engage and captivate audiences.

Furthermore, the use of soft technologies for expressive purposes in this project opens up a range of creative possibilities for future projects. Soft robotics technology has the potential to be used in a variety of expressive applications, from art installations to interactive toys, and can create lifelike and engaging movements that mimic natural forms. The technology also allows for a level of customization and flexibility that is difficult to achieve with traditional robotics, as the soft materials can be molded and shaped into a variety of forms.

Outcomes

Successes:

1. The project successfully utilized soft robotics technology to create a unique and engaging sculpture that mimics the organic movements of plants.
2. The use of silicone-based parts allowed for a lifelike and flexible appearance, which contributed to the immersive experience for the viewer.
3. The capacitive touch sensing technology provided an interactive element to the sculpture and allowed for a direct connection between the viewer and the movement of the sculpture.
4. We successfully implemented an FSM in circuit python to control the movement of the motors which resulted in varied inflating and deflating motions for the plants.
5. The iterative design process led to the creation of some cool and unique silicone parts.

Failures:

1. The range of motion for the Venus fly-trap as well as the flowers was limited.
2. The use of acetate as a rigid and inflexible material for the leaves of the venus-fly trap resulted in a less organic and lifelike appearance for this part of the sculpture.
3. The project did not fully explore the potential of machine learning algorithms to create more nuanced and lifelike movements.
4. The project did not fully explore the use of alternative actuation methods, such as shape memory alloys or electroactive polymers, to achieve a higher range of motion for the venus fly-trap leaves.

Photographs

Citations

https://robotreporters.com/the-robotic-venus-flytrap-and-other-bio-inspired-soft-robot-actuators-psas-from-purdue-university/

Technical Documentation

• Codebase: https://drive.google.com/file/d/1PW6Rl5aj-DYl_8-PLJQsC3fAFIf5Q_uT/view?usp=share_link 
• CAD Flytrap: https://drive.google.com/file/d/1Xm4FTwDL6hjF1uotGPG8O9Ds15u_xU2T/view?usp=share_link 
• CAD Flower: https://drive.google.com/file/d/1res6GHl9D_EOqtkSACYrhW3BDqG5zrRN/view?usp=share_link 

Contributors

Aditti Ramsisaria:

• Mold design for fly-trap actuator and flower
• Electronics and code for pneumatic actuation
• Acetate mesh wiring

Catherine Liu:

• Silicone fabrication of parts
• Acetate mesh design and laser cutting

Both:

• Concept and implementation ideation

Additionally, we weaved and embedded an electrode for the capacitive touch sensor through acetate and bonded that to the silicone flower we cast earlier.

This week we will be casting the leaves and embedded electrodes in them, bonding them to the actuator and working on motor electronics.

Moving forward, we are going to stick to the original actuator and attach leaves to it to test out our electronics. We will also try our another bending design for the fly trap this week with leaves attached to the actuator.

We also laser cut a piece of acetate (PET) to add more stiffness to generate more of a differential for our flower design. We will be embedding it in the coming week.

We also tried embedding an electrode attached to a capacitive touch sensor inside our venus fly trap actuator to ensure that we can recalibrate it to respond to surface touch.

Lastly, we worked on another design for our venus flytrap actuator with ridges to try to get more of a bend during inflation. We will be printing and casting this part in the coming week as well.

Continuing from class discussions on plants, I remembered Edwin Tinney Brewster’s book titled Natural Wonders Every Child Should Know, particularly a writing that highlighted the delicate balance between life and death in a tree, questioning how much of a tree is alive, which biologically, is close to only 1%. Considering various philosophical distinctions on the subject sent me down a spiral of biological essentialism, process philosophy, and panpsychism. This brought me to my question – if a plant could grow, reproduce, adapt to its environment, move, and have behavioral characteristics that could convey bio-electrochemical signals would it be considered as alive as a human?

I came across MIT’s plant-robot hybrid that used the plant’s own internal electrical signals to interface with a robotic extension that drove it toward light, and thought it was insanely cool.

In this setup, electrodes were inserted into stems and ground, leaf and ground to catch traces of bio-electrochemical signals produced in response to changes in light, gravity, mechanical stimulation, temperature, wounding, and other environmental conditions. These signals were then amplified and triggered movements.

I then found another plant locomotor that I thought could be adapted into a soft robotic form:

The six-legged robot can carry a plant on its back, and aside from achieving the purpose of moving towards sunlight, its also incredibly cute. Plants, which are considered to have the most passive existence, being able to freely move around, play with humans and throw a tantrum when it needs watering reminded me more of a pet than a plant.

I want to combine these ideas to make something akin to a legged soft robotic plant locomotor that relies on bio-electrochemical signals (like the MIT project) from plants to trigger behaviours that make sense to humans (like the Vincross project). I think the compliance of the soft robot lends itself to the image of a typical houseplant, and can offer the capabilities of a traditional robot with pneumatic actuation. Eventually, I want to integrate the plant and robot even closer by growing plants in hydrogels than can be interfaced with the soft robot.

A potentially relevant paper I found was: Drotman D, Jadhav S, Sharp D, Chan C, Tolley MT. Electronics-free pneumatic circuits for controlling soft-legged robots. Sci Robot. 2021 Feb 17;6(51):eaay2627. doi: https://doi.org/10.1126/scirobotics.aay2627.

This paper proposes a fully pneumatic (electronics-free) system for controlling a basic omni-directional walking gait that could respond to sensor input.

Other papers:

https://www.semanticscholar.org/paper/Cyborg-Botany%3A-Augmented-Plants-as-Sensors%2C-and-Sareen-Zheng/90755d2285f93bb725c5fe6fd7f3235fe000489b#citing-papers

By giving plants a few more degrees of freedom, I hope this project can bring some light to a holistic, nature-centric view of technological evolution.

The Interactive Birds installation by Chico MacMurtrie at Amorphic Robot Works uses Inflatable Robots to create the wing-like structures of birds. What I find cool about this installation is the concept and the underlying theme that influenced the programming, rather than the actual installation itself. The “birds” are made using white fabrics that hang limp initially and then inflate by sensing viewers in the room, leading into a slow flapping motion through pneumatic actuation. But if viewers encroach upon the space excessively, the birds become “infected” and begin to corrupt the others, leading to premature death. I thought this was a fitting theme to signify how human intervention affects life cycles in nature.

Here are some other interesting links of soft robotic artwork that I found during this process:

1. Exo-biote: https://3dprint.com/93771/soft-robotics-exo-biote/
2. Soft Robotics and Posthuman Entities: https://www.researchcatalogue.net/view/549014/605906/50
3. Inflatable breathing: https://www.designboom.com/technology/inflatable-sculpture-soft-robotics-breathing-pulse-mateo-fernandez-01-04-2023/

Referee Form:

1. Do you have any conflict of interest in reviewing this paper?

No

2. Expertise. Provide your expertise in the topic area of this paper.

1 – No Knowledge

3. Summary. Please summarize what you believe are the paper’s main contributions to the field of soft robotics.

This paper proposes a fabrication method for reconfigurable motile soft micromachines with compound bodies that respond to external control signals using magnetic control for mobility and spatiotemporally controlled heating for shape-shifting. The paper illustrates through various studies that the coupled effect of mobility modulation with the morphological transformation of the tail as well as the body determines swimming efficiency. The paper advances the field of soft robotics by introducing an origami-inspired rapid prototyping process for a novel microbot made of soft materials that can navigate complex and varied environments with its reconfigurable shape and motility. This ability can be leveraged in minimally invasive environmental and biomedical procedures which often comprise heterogeneous environments.

4. Strengths and Weaknesses. What are the main strengths and weaknesses of this work? Does the paper have strengths in originality and novelty?

The paper’s biggest strength is the novelty of the proposed mechanism and how it provides a holistic and comprehensive solution to various niche problems in bioinspired soft micro-robotics. It introduces a mechanism to fabricate a variety of bioinspired flagellated micromachines with varied forms such as the long slender form and stumpy form inspired by the Trypanosoma brucei as well as other forms such as a tubular body with a helical/spiral tail, and a helical body with a planar tail using morphological transformations actuated by magnetic and thermal signals. It lists in detail the methodology – from material specifications and patterning using lithographic techniques to machine architecture through particle alignment and morphological variations from thermal control. The figures illustrate the descriptions of motion and morphology well, and a lot of supplementary material is provided for reference. The paper also mentions unexpected findings that indicate the authenticity of the results. The one weakness of the experiments is that the different micro-swimmers were not tested in multiple environments, which the paper claims is one of the crucial contributions of the study. The different configurations are only tested in a viscous sucrose solution with a Reynolds number between 0.1 and 0.001.

5. Soundness. Are the ideas, algorithms, results, or studies technologically/methodologically sound?

I believe the paper is methodologically sound. To demonstrate the diverse capabilities of the composite material, the authors provide extensive analytical and empirical evidence and quantifiable metrics and data to evaluate performance. The authors also give a convincing argument supported by evidence for the independence in the effects of magnetization and thermally induced morphological manipulation, and how the coupled results affect folding along different axes and propulsion. The experiments also use sound methodology for collecting 3D trajectory data using 2 orthogonal cameras visualizing the workspace from the side and top views.

6. Related Work. Does the paper adequately describe related and prior work?

I believe the paper adequately describes previous/related work. The introduction mentions and analyses various works related to artificial micro-swimmers (typically inspired by flagellated structures like E. Coli) and various techniques for propulsion in a corkscrew-like motion. It also surveys and provides background on different techniques in the methodology for design and manufacturing, programming machine architecture through MNP alignment, programming triggered transformation of morphology using NIR heating, as well as propulsion.

7. Presentation. Is the paper well-organized, well-written, and clearly presented?

The paper is well-organized and presented. The methodology is broken down into multiple sections with a clear and concise logical flow. The paper begins with an introduction of the inspiration behind the design and a literature review, followed by results and methodology along with a discussion of the results.

8. Suggestions. Do you have suggestions for improving this paper? Please write several paragraphs detailing specific points of the paper that merit reconsideration. Be sure to address the text, figures and tables, mathematics, and grammar and spelling.

For the most part, the text, figures, and tables are clear in their labelling, context, and conclusions. Although I would have appreciated more contextual information in some areas, for example,  in the usage of Timoshenko bimorph beam theory, I understand that researchers in the field are more familiar with such concepts than me.

Another suggestion would be to conduct studies in different fluid environments that closely resemble the use cases for the proposed micro-swimmers. For example, the paper mentions “transforming a conical head into a helical one may enable superior mobility in highly viscous fluids (as mastered by Spirochetes), while transforming back to the original shape may facilitate tissue penetration” as a use case, but the device itself does not demonstrate these capabilities as it was not tested in a heterogeneous environment.

I appreciated the organization of the paper but would suggest making supplementary materials/data publicly available instead of making it available on request, which could help with the verification of results.

9. Comments to Committee (Hidden from authors). Does the paper have enough originality and importance to merit publication? Is the paper relevant to the field?

I believe this paper has enough originality and importance to merit publication. Papers in the past have largely only considered the flagella (i.e. the tail) in actuation propulsion in flagellated artificial micro-swimmers. The paper proposes a novel mechanism that considers the coupled effects between the cell body and the flagella instead of just the flagellar propulsion mechanism. The paper also considers the motion of Trypanosoma brucei which can adapt its shape and respond to the environment by exploiting soft and stiff structures as opposed to controlled swimming motion, instead of the usual flagellated structures inspired by E. Coli. The novelty of this approach backed by technical soundness and empirical evidence warrants the publication of this paper.

10. Overall Rating. Provide your overall rating of the paper (5 is best)

5 – Definite accept: I would argue strongly for accepting this paper.

This paper details a 3D-printed, tetherless, inchworm-inspired soft robot using magnetic actuation for linear locomotion and crawling, with multi-material composition (magnetic particle–polymer composite and flexible polymer) achieving a stride length of 5mm, a linear locomotion efficiency of 93.28% and maximum bending deformation of 4.5mm.

Paper 2: Miriyev, Aslan & Stack, Kenneth & Lipson, Hod. (2017). Soft material for soft actuators. Nature Communications. 8. https://doi.org/10.1038/s41467-017-00685-3.

This paper proposes a soft robust composite material that combines the elastic properties of a polymeric matrix and the extreme volume change accompanying the liquid-vapor transition to develop a self-contained electrically driven soft actuator that can be used as an artificial muscle.

Paper 3: Baghbani Kordmahale, S., Qu, J., Muliana, A. et al. A hydraulic soft microgripper for biological studies. Sci Rep 12, 21403 (2022). https://doi.org/10.1038/s41598-022-25713-1.

This paper details a microscale hydraulic soft gripper built on PDMS that could be used to manipulate an ant without damage. The gripper consists of three finger-like columns on a circular membrane which could be opened/closed by varying the pressure inside a cavity.

Other Related Papers:

Lyu, Liang & Li, Fen & Wu, Kang & Deng, Pan & Jeong, Seunghee & Wu, Zhigang & Ding, Han. (2019). Bio-inspired untethered fully soft robots in liquid actuated by induced energy gradients. National Science Review. 6. 970-981. https://doi.org/10.1093/nsr/nwz083.

Huang, H., Sakar, M.S., Petruska, A.J., Pané, S., & Nelson, B.J. (2016). Soft micromachines with programmable motility and morphology. Nature Communications, 7. https://doi.org/10.1038/ncomms12263