3.2 EAPs Manufacturing

1. Cut Nafion-117 into 2 x 1cm x 5cm, 2 x 2cm x 5cm, 2x 1cm x 10cm, 1 x 2cm x 10cm.
2. Roughen the surface of Nafion-117 polymer by sandpapering.
3. Prepare an aqueous solution of the complex ([Pt(NH3)4]Cl2 or [Pt(NH3)6]Cl4).
4. Place the one cut of the polymer in the stirring Pt solution at 60◦C for 1 hour.
5. When Pt particles have immersed into the polymer, add 5% N₂H₄·H₂SO₄ solution.
6. When grey metallic layers form on the membrane surface, finish the experiment.
7. Repeat the process.

3.3 Performance Testing 

Dry Test:

Using ATTEN TPR3003T’s Regular DC Power Supply and 2 pieces of conductive tape on both sides of the IPMCs polymer.

Modify the voltage from 0V to 30V to activate the polymer. Then modify the current from 0.1A to 10A to supply different intensity electric field level with the combination of various voltage.

Underwater Test:

Using ATTEN TPR3003T’s Regular DC Power Supply and 2 pieces of wire with an insulating layer on the side surface touching both sides of the IPMCs polymer.

Modify the voltage from 0V to 30V to activate the polymer. Then modify the current from 0.1A to 3A to supply different intensity electric field level with the combination of various voltage.

Experiment Results Analysis

First Experiment Result: Failed

Reasons’ Analytic Report:

1. The previous stirring time is not enough for Pt ions to attach on the surface of the polymer.
2. The  NaBH4 solution was mixed with the Pt solution, which caused waste of the Pt ions in solution.
3. The concentration of the ammonium hydroxide solution is too high and caused the high pH level of the solution. Finally, it results in the precipitation of Pt.

Second Experiment Result: Half Success

Reasons’ Analytic Report:

1. The oxygen in the open air oxidized the Pt that was successfully attached to the polymer.
2. The Pt on the polymer is still not enough after a single round of the experiment. The above procedures need to be repeated 3-5 times to ensure the efficiency of the polymer.

Third Experiment Result: Half Success

Reasons’ Analytic Report:

1. Tried to use a higher concentration of NaBH4 solution. However, it turned out to be too much. The Pt that had already attached on the surface in previous steps drop down because of the fierce bubbles caused by the reaction.
2. The time is so limited that the reaction is not fully completed.

Fourth Experiment Result: Success

Reasons’ Analytic Report:

1. Cut the edge of the polymer in order to avoid the electricity to go through the edge to another surface.
2. Substituted the NaBH₄ by the N₂H₄·H₂SO₄. This change narrowed down the cost of manufacture.

Figures and Videos for Step 3.2 & 3.3

                 

 

Step 1: Plan

After the in-class discussion, we decided to make a collective decision project called “Gathering Up”.

Main Procedures: 

1. During the project, keep sending the (x, y) position to the Robotbits.
2. The 5 Robotbits will be spread on the ground.
3. The 5 Microbits will calculate the distances between every 2 Robotbits.
4. Every 2 Robotbits that are close to each other will gather together.
5. The Microbits will calculate the distances between every 2 groups of Robotbits.
6. The most closed 2 groups of Robotbits will gather up.
7. The 5 Robotbits are all clustered.
8. The 5 Microbits display “Robotbits Assemble!!” (and maybe an audio clip).

Materials:

Microbit x 5

Robotbit set x 4 (optional)

HD 920c Logitech camera

Mac mini

Aruco markers

|

Anaconda-Navigator

OpenCV Library

Mu-Editor

Microbit Wireless Communication Module

Step 2: Code

Code for Computer Vision:

https://github.com/todocono/arUco

Code for Robotbit communication:

https://github.com/todocono/birs2019s

Additional Resources from Github Repository:

https://github.com/krawc/arUco

Step 3: Reflect on the process

The collective decision is really a challenging topic to address.

It requires many technical skills like the application of openCV and wireless communications between Microbits.

Besides, it needs a whole group of student (for example, we have 5 people in our group) to adjust their schedule to create a perfect time for all of the members to work on the project.

However, the process of making the project is exciting and interesting. 

Most importantly, we learned a lot from this collaboration.

Artificial Muscle Based on Electroactive Polymers:

A New Foundation for Bio-inspired Robotics

Gengyu Chen and Yile Xu

Department of Interactive Media Arts, New York University Shanghai, Shanghai, China

(Tel : +86-131-670-51591; E-mail: gc2370@nyu.edu)

(Tel : +86-186-658-00487; E-mail: xy1242@nyu.edu)

Abstract: To break the limitations and barriers of tradition locomotion design in robotics, this paper focused on a new material: Ionic Polymer-Metal Composites (IPMCs), which is a subset of Electroactive Polymers (EAPs). This kind of material can conduct movements such as shrink and stretch under a low voltage. It can function as artificial muscles for a new foundation of robotics design. The paper explored easy producing procedures from Nafion 177 to IPMCs and the following procedures from IPMCs to the artificial muscle, along with some theoretical knowledge about EAPs and IPMCs. Then the paper presented qualitative testing data for the material and possible further application of using this kind of artificial muscle in bio-inspired robotics.

Keywords: IPMCs, EAPs, Artificial Muscle, Bio-Inspired Robotics.

1. INTRODUCTION

The mainstream for robots’ locomotion design is to use motors, servos, and other metallic compartments. Although they seem to function well, they are different from real animal movements. Thus, they have certain limitations and drawbacks. Therefore, Researchers have been trying to design new locomotion systems for robots, but there are only a few results.

This paper provides a foundation for a new locomotion system design, by studying a widely-ignored material: Electroactive polymers (EAPs), especially on one of its type: Ionic Polymer-Metal Composites (IPMCs). This type of material will shrink when providing low voltages onto its surface, and stretch when removing the voltages.

EAP material was firstly invented by a material scientist named Wilhelm Rontgen.[1] Then in the 1960s, a breakthrough of EAPs took place, and the first electrically conducting polymers were discovered by Hideki Shirakawa.[2] In the early 1990s, IPMCs were developed and appeared to be much more effective compared to EAPs.[3] It needs only 1 or 2 volts to motivate, and this became a significant discovery for the bio-inspired robotics’ development.

However, the artificial muscle made of IPMCs is still hard to be manufactured, and the quality of the material is still beyond control. Thus, base on previous research done by other scientists, The paper discovers a simple procedure for university students to produce their own artificial muscle from EAPs, and find ways to apply this new kind of artificial muscle to the bio-inspired robotics.

1. Electroactive Polymers and Ionic Polymer-Metal Composites

EAP materials have two categories, Dielectric Electroactive Polymers (DEAP), whose squeezing and stretching behavior is caused by electrostatic forces on the surfaces. The force stretches and squeezes the insulated polymers in the middle. This type of material is resilient and relatively easy to manufacture. However, it requires thousands of volts to function. The other type is Ionic Electroactive Polymers (IEAP), which is represented by IPMCs. The material is made up of a cation or anion exchange polymer with its two sides plated by metals. When being added voltages, the surfaces creates an electric field in the polymer, moving the corresponding ion to one side. However, the detailed theory behind its behavior is not fully understood.

1. Experiment Design

3.1 Material Preparation

Equipment: Beaker, Glass Rod, Dropper, Test Tube, Forceps, Water Bath, pH test paper.

Reagents: 10cm x 10 cm Nafion-117 Polymer, Platinum standard solution, diluted hydrochloric acid, 1% ammonium hydroxide solution, 10% NaBH4

3.2 EAPs Manufacturing

1. Cut Nafion-117 into 2 x 1cm x 5cm, 2 x 2cm x 5cm, 2x 1cm x 10cm, 1 x 2cm x 10cm.
2. Roughen the surface of Nafion-117 polymer by sandpapering.
3. Mix Pt solution with ammonium hydroxide until pH is 3.
4. Place the one cut of the polymer in the stirring Pt solution at 80◦C for 5 minutes.
5. Move the polymer to NaBH4  solution at 50◦C, and observed bubbles emerge on the polymer. Wait for the reaction to be over.
6. Repeat process 4-5
7. When dense grey metallic layers form on the membrane surface, finish the experiment.

3.3 Performance Testing

Dry Test:

Using ATTEN TPR3003T’s Regular DC Power Supply and two pieces of conductive tape on both sides of the IPMCs polymer.

Modify the voltage from 0V to 30V to activate the polymer. Then modify the current from 0.1A to 10A to supply different intensity electric field level with the combination of various voltage.

Underwater Test:

Using ATTEN TPR3003T’s Regular DC Power Supply and two pieces of wire with an insulating layer on the side surface touching both sides of the IPMCs polymer.

Modify the voltage from 0V to 30V to activate the polymer. Then modify the current from 0.1A to 3A to supply different intensity electric field level with the combination of various voltage.

1. Experiment Process Record

Lab Record:

Final Project’s Documentation (Artificial Muscle Based on Electroactive Polymers: A New Foundation for Bio-inspired Robotics)

Link to the Record:

https://wp.nyu.edu/shanghai-ima-documentation/uncategorized/xy1242/lab-report-final-project-artificial-muscle-documentation-draft/

1. Experiment Results Analysis

First Experiment Result: Failed

Reasons’ Analytic Report:

1. The previous stirring time is not enough for Pt ions to attach on the surface of the polymer.
2. The  NaBH4 solution was mixed with the Pt solution, which caused waste of the Pt ions in solution.
3. The concentration of the ammonium hydroxide solution is too high and caused the high pH level of the solution. Finally, it results in the precipitation of Pt.

Second Experiment Result: Half Success

Reasons’ Analytic Report:

1. The oxygen in the open air oxidized the Pt that was successfully attached to the polymer.
2. The Pt on the polymer is still not enough after a single round of the experiment. The above procedures need to be repeated 3-5 times to ensure the efficiency of the polymer.

 

Third Experiment Result: Half Success

Reasons’ Analytic Report:

1. Tried to use a higher concentration of NaBH4 solution. However, it turned out to be too much. The Pt that had already attached on the surface in previous steps drop down because of the fierce bubbles caused by the reaction.
2. The time is so limited that the reaction is not fully completed.

Fourth Experiment Result: Success

Reasons’ Analytic Report:

1. Cut the edge of the polymer in order to avoid the electricity to go through the edge to another surface.
2. Substituted the NaBH₄ by the N₂H₄·H₂SO₄. This change narrowed down the cost of manufacture.

1. Further Development

6.1 Heart, Lung, and Jellyfish:

Heart, lung, and the propulsion locomotion of jellyfish are similar: the muscle expands, creating a negative pressure to draw in blood, air, or water, then the muscle contracts to push them out. They can be implemented by our material.

Using the IPMCs based artificial muscle as the jellyfish’s muscle underwater is feasible. The Microbit and related editor like mu-editor can be used to do the physical computing part and provide periodical voltage. The basic movement like moving forward and blood cycle can be achieved by applying different intensity of the electric field.

 

6.2 Arms, Legs, and Bio-Inspired Seahorse Robotic:

The Seahorse Robotic might be the best robotic to utilize the feature of IPMCs based artificial muscle thoroughly. By using the IPMCs with less Pt density to build the top half part of the seahorse robotic and use the more Pt density one to build the bottom half. The IPMCs’ feature of having a different shrinking and stretching level under different Pt density and electric field intensity. It is similar with robotic arms and legs, where the IPMCs connects with to bones, which are assembled by a joint.

 

References

[1] Keplinger, Christoph; Kaltenbrunner, Martin; Arnold,

Nikita; Bauer, Siegfried (2010-03-09).

“Röntgen’s electrode-free elastomer actuators without electromechanical pull-in instability”. Proceedings of the National Academy of Sciences. 107 (10): 4505–4510. doi:10.1073/pnas.0913461107. ISSN 0027-8424. PMC 2825178. PMID 20173097.

[2] “Electrochemistry Encyclopedia: Electroactive

Polymers (EAP)”. Archived from the original on 2012-12-12.

[3] Finkenstadt, Victoria L. (2005). “Natural

polysaccharides as electroactive polymers”. Appl Microbiol Biotechnol. 67 (6): 735–745. doi:10.1007/s00253-005-1931-4. PMID 15724215.

 

Step 1: Get ready

1. No open-toe shoes.
2. No shorts/short skirt or dress.
3. No eating or drinking in the lab. We do provide a shelf for school bags, water bottles and such. No opened food or drink is allowed in the lab.
4. Long hair must be tied up.
5. Use a proper channel to report medical conditions related to this lab. This lab will use live fruit fly for observational purpose. This lab will use latex gloves.

Step 2: Documentary

     

Step 3: Analyze your results

Method:

Column 1. Index at reading (from 1)
Column 2. Date of reading
Column 3. Time of reading. Please start from line 13. 16:00:00. From this time on all monitors are read once every hour.
Column 4. Monitor status. 1= valid data received.
Column 5 to 10 are not used in this experiment.
Column 11. Channel 1
Column 12. Channel 2
…
Column 42. Channel 32

When looking through the data column returned from the biology lab, we can discover the activity regularity of flies.

In tube No. 1-2 6-10 12-13 16: 

The activity of flies seems inconspicuous at all.

This phenomenon might be caused by:

1. We wrongly put in too much CO2 into the tube, and the flies are always sleeping or even have already died because of the high concentration of CO2 gas in the tube.

2. We accidentally stuck the stickers onto the wrong positions and blocked the light sensors so that the sensors didn’t work.

3. The sensors might have broken.

In tube No. 3-5:

The activity of the flies lasts for almost all days.

This phenomenon might be caused by:

The lack of the gene that shut down its circadian rhythm.

In tube No. 11 14-15:

The activity of the flies is regular.

This phenomenon might be caused by:

The normal circadian rhythm that the flies have.

Step 4: Conclusions

We learned in the course that the lack of one kind of genotype of the flies might lead to the disorder of circadian rhythm behavior. And caused the irregular activities of flies.

And also, we learned about how the scientific community approaches the results of these experiments. When doing an academic experiment, scientists will first make sure the safety conditions. Then, planning the experiment step by step. Thinking what might happen during the experiment and thinking of how to deal with the possible result. After that, scientists will do the experiment as scheduled. And finally, analyze the data from the experiment to make discoveries. These rigorous steps are all necessary for a successful scientific experiment.

When connecting these to my own experiences when developing robots and software for our class, the first thing I thought about is the animal behavior observation we did in the course lab. However, it is a brand new feeling when we can actually observe the creatures in this experimental way. It can provide us more specific patterns of the creatures than just staring at them or watching video from Youtube. So I consider it as a precious chance to discover the biology observation part of our bio-inspired robot system’s development.

Besides, since Kris and I decide to do more experimental attempt in our final project. I think it is a really good pre-req experience for us to conduct a relatively good experiment for our project. I believe we will keep working on the experimental discovery and keep making progress.

Kris and I decided to make a robot jellyfish that can control the height after watching the beautiful jellyfish movement on YouTube like this.

However, it is kind of hard to keep the micro: bit board dry under the water. And also, we thought it will be more fascinating if the jellyfish can swimming in the air, we decided to make it as a flying robot jellyfish.

How Will We Make It

1. structure
We decided to make jellyfish-like double-layer membrane filled with helium to make it able to maintain its position in the sky without falling down. (It is mainly to save power, else the propulsion part will have to keep running)

2. control
We decided to use micro: bit with robotbit as before. In addition, we need a voltage transformer this time to support our propulsion part.

3. movement
The most exciting case, also the most difficult one, is that we will design, test and make special Electroactive Polymers (EAPs). It is a material that will shrink sharply when receiving electrical current or field. So, it can act as artificial muscle to simulate in inhalation and exhalation (propulsion) of jellyfish.
After researching, we discovered a way to make it: using a PDMS membrane and Graphene.
However, as EAPs material is advanced material science, there are chances that the result might be not as we expected. So I prepared a backup plan: just using helicopter fans to propel it.

4. power
Currently, we have 3 options:
a. use battery (most simple, but might be heavy and not good looking for the jellyfish)
b. wireless power (requires some extra knowledge technologies and experiments)
c. solar power board (expensive)

5. detailed modification
Mainly decoration, testing, programming and changing argument in software.

Source