Final - Wedyan HTMAA

Idea 2: Initial Experimentation with Co2 Laser

I have been using the GCC CO2 laser at CBA in order to create my material

Method: Direct laser writing on polyimide substrate to generate laser-induced graphene (LIG) !

Why graphene will be used as?

Coating → Makes droplet highly mobile without bath

Substrate → can be the conductive circuit+ sensing for location mapping

Used different power, speed and laser pulse density to find the optimal 30 Watt laser

For 3 mm thickness older substrate : Power : 11% , Speed 3%, 1000 PPI

Still need to optimize further → nonuniformity

Due to laser bed not being completely levelled

Idea 2: Initial Experimentation with magnetic actuation

Source 1 , Source 2 , Source 3

I have been doing some reading in the literature, and my observation is that most people trying to move gallium-based liquid metals magnetically are either adding it in its electrolyte bath or using a permanent magnet. In all cases, the LM droplet has to be coated with magnetic particles such as iron to actuate it. Ideally, I would like to use an electromagnet for control, and I would like it to be in a dry environment so that I can read resistance variations reflected on my LIG patterned substrate

As part of the output week, I experimented with different forms of electromagnets, commercial ones and one I made by myself. As of now, I cannot generate enough magnetic force to pull the droplet to the adjacent electromagnet. I am planning to read more about electromagnet designs and better understand how to design the optimal one for me and if it is a feasible mechanism for what i am trying to achieve. Additionally, I am using relatively large iron particles, using nanoparticles should improve the homogeneity of the liquid metal slug. Below you will find two videos, in the first one, I am moving my iron mixed LM droplet with a permanent magnet. On the other video, I am attempting to move it with the electromagnet, but it was not enough

I initially used iron particles with a large diameter that I got from Amazon. When I tried to coat my LM droplet with those, it was quite problematic. Since they were big and did not miz well with the LM, when I try to move the droplet with a permanent magnet, the iron particle starts to poke out of the LM droplet, exposing some of the inner LM core, which is sticky and problematic.

Then, I found finer powder of iron particles with a diameter of 10 micrometers. I did a quick coating of a random amount of the powder at the surface of LM droplet. It was easier to mix and as you can see it forms a nice coating around and I was able to move it over the LIG electrode as shown in the video below.

Initial experimentation with magnetic actuation

LM actuation with permanent magnet

LIG electrode resistance variation as a function of LM droplet location

Intial LM slug actuation test with commercial electromagnets

Reference work : Magman by Jiří Zemánek , a former CBA postdoc.

Final Project Details : Dancing Drops

Summary Slide

Final Project in Action!

The video below demonstrates the implementation described above:

Sequential actuation of the liquid metal droplets by a sequential triggering of the electromagnets

Attempt to make dancing liquid metal drops!

Demo from HTMAA 2022 Open House

My original idea for the project was to integrate both actuation and feedback into the system. The feedback component will consist of a substrate patterned with conductive material where the liquid metal will connect and disconnect between electrodes. Thus, I focused most of my efforts on actuation and did not get the time to integrate the sensing element within the system. However, below I demonstrate the functionality of the droplet once it passes through two electrodes made out of indium tin oxide on glass. As seen in the video, once the conductive liquid metal droplet makes contact between the two electrodes, it allows current to pass through, triggering the switch.

What does it do?

It is a programmable LM droplet control platform. It enables manipulation of magnetic LM droplets using an array of electromagnets. The on-demand transportation deformation Splitting merging of multiple MLM droplets simultaneously and precisely will enable in the future applications such as

Dynamically reconfigurable circuits

Liquid metal switch/transistor

Programmable droplet-robots

Shape display

Who's done what beforehand?

The deformability and conductivity of liquid metal droplet has been leveraged and used as a moving robot that can reconfigure, travel inside narrow and constrained spaces without damaging the interfaces due to their extreme deformability and liquid nature. Researchers have explored multiple actuation techniques of those droplet-based robot including magnetic field, electric filed, or electrochemical reaction and pneumatically using pressure. Early one, I picked to go with the magnetic actuations since I had a goal of using it in a dry environment. However, after experimenting and implementation, I realized how hard it is to get rid of the electrolyte bath. Thus, I ended up using it too.

What did you design?

I designed and fabricated the electromagnets by coiling enabled copper wire into a soft iron core with a drill and 3D printed sleeve. Additionally, I PCB to control and drive each electromagnet separately. Serial communication between my computer and the platform for controlled actuation. Finally, I designed the case and packaging of the platform

What materials and components were used?

Where did they come from?

How much did they cost?

What parts and systems were made?

Electromagnets

3d printed sleeves for electromagnets coil

Coil winding

PCB breakout boards (Milling and soldering)

Case

Laser Cutting

Processor

ESP32 Board

What processes were used?

Solidworks (3d modeling)

Corel Draw (laser cutting)

3d printing (electromagnets)

Laser cutting (case)

Arduino IDE (sending code)

PCB milling

Soldering

Wet processes (magnetic liquid metal droplet preparation)

What questions were answered?

Can gallium based liquid metal droplet be actuated using magnetic field in a precise manner?

Can magnetically actuated gallium based liquid metal droplet be used as a movable switch?

How can multiple electromagnets be controlled via serial communication?

What worked? What didn't?

What worked:

Mixing gallium-based liquid metal with iron nanoparticle powered and hydrochloric made the liquid metal magnetically responsive.

Immersing liquid metal in its electrolyte bath (Sodium Hydroxide) facilitated its mobility

Electromagnet control PCB of 2 by 2 electromagnets worked and actuated the magnetic LM droplet

What did not work:

Actuating LM droplet without a magnetic particle coating

Actuating the LM droplet in a dry environment using graphene coating  after mixing with iron particles, as the core of the LM is now magnetic too, the core is being attracted to the electromagnet at the bottom of the substrate which causes the droplet to burst, exposing the LM sticky core and hindering mobility of the droplet

Electromagnet control PCB of 3 by 3 electromagnets did not work , I was only able to actuate 5 out of 4 electromagnets. It requires debugging.