Advaith Menon

Week 1

This week, I dedicated time to writing up the proposal for changes to be made to the spin coater, ensuring that all necessary modifications were clearly outlined to improve its efficiency and functionality. I had planned to coordinate with Anirud on a call to discuss dimensional specifications, but unfortunately, scheduling conflicts prevented the meeting from happening. However, despite this setback, I was able to make progress in other areas by joining the Fusion file and actively working on the prototype for versions 2 and 3. This stage of development is crucial as I refine the design and implement improvements based on previous iterations. Moving forward, I plan to continue prototyping while also rescheduling the call with Anirud to finalize key specifications and ensure that everything is on track.

Week 2

This week, I was focused on material selection and design considerations for the Spin Coater, particularly evaluating options for the transparent lid and non-transparent body. A key part of this process involved comparing thermal resistance, transparency, impact resistance, machinability, and cost for different materials to ensure the chosen components can withstand the operating conditions of the spin coater while maintaining affordability and ease of fabrication.

Additionally, I began research on a linear slide system to improve precision in the spin coating process. The goal is to enable controlled movement of the actual spincoater, allowing it to switch from the liquid handling system to the annealing system. This research involves evaluating different slide mechanisms, materials, and motion control methods to integrate with the spin coater effectively.

Material Selection & Properties Analysis

To ensure the spin coater operates effectively under heat and mechanical stress, I analyzed various polymers based on their deflection temperature, melting point, and durability. This was necessary for choosing materials that will not degrade under repeated exposure to heat and solvents during the spin-coating process.

Polymer Property Comparison

Polymer Type

Deflection Temperature at 0.46 MPa (°C)

Deflection Temperature at 1.8 MPa (°C)

Melting Point (°C)

ABS

Acetal Copolymer

160

110

200

Acrylic

130

Polycarbonate

140

130

Polyethylene Terephthalate (PET)

250

Polypropylene

100

160

Polystyrene

Key Observations:

ABS and Acetal Copolymer offer high durability and machinability, making them strong candidates for structural components.
Polycarbonate and Acrylic provide clarity for transparent parts but differ in heat resistance and durability.
Quartz, though more expensive, offers the highest thermal stability and optical clarity, making it a strong contender for the lid.

Lid Material Selection

Since the lid must be transparent, I evaluated Acrylic, Quartz, and Polycarbonate for their infrared transparency, impact resistance, and heat resistance.

Lid Material Comparison

Property

Quartz (Fused Silica)

Acrylic (PMMA)

Polycarbonate (PC)

IR Transparency

250 nm – 3,500 nm (excellent)

750 nm – 2,000 nm (good)

700 nm – 1,100 nm (limited)

Visible Transparency

High (clear)

Slightly less clear

Thermal Stability

>1,000°C (excellent)

~100°C (softens)

~120°C (better than PMMA)

Impact Resistance

Brittle

Moderate

High

Durability

Scratch-resistant but fragile

Easy to scratch

Scratch-resistant but softer than quartz

Machinability

Difficult (requires special tools)

Easy (drill, cut, laser)

Easy (similar to PMMA)

Chemical Resistance

High (resists acids, alkalis)

Moderate (resists weak acids)

Poor (degrades with solvents like acetone)

Cost

Moderate ($$)

Low ($)

Moderate ($$)

Weight

Heavy

Lightweight

Final Decision:

Quartz is the best choice for thermal stability and optical properties, ensuring it can withstand long-term usage without deformation.
Acrylic is the most affordable but softens at high temperatures, making it a risky choice for prolonged exposure to heat.
Polycarbonate is more impact-resistant than acrylic but does not handle solvents well, which is a drawback.

I believe that for an initial prototype, acrylic would be best

Non-Transparent Parts: Structural Material Selection

The non-transparent parts of the spin coater need to be rigid, durable, and easy to manufacture. After comparing various options, ABS was selected for the following reasons:

Cost-Effective – It is inexpensive compared to alternatives.
3D Printable – Allows for rapid prototyping and customization.
Durable and Heat Resistant – Withstands mechanical stress and moderate heat exposure.

Material Procurement

To move forward with testing, I compiled purchase links for the different materials:

Acrylic Sheet: Amazon Link
Quartz Sheet: Amazon Link
Polycarbonate Sheet: Amazon Link

Current Research: Linear Slide System for the Spin Coater

To enhance the precision and automation of the spin-coating process, I am investigating a linear slide system. This system will allow controlled movement of the sample stage or dispensing nozzle, ensuring uniform coating thickness and reproducibility.

Key Design Considerations for the Linear Slide System

1. Motion Mechanism

Linear Rails with Bearings → Provide smooth, low-friction movement.
Lead Screw System → Ensures precise motion but is slower.
Belt-Driven System → Faster but less precise.

2. Actuation & Control Options

Stepper Motor Control → Allows programmable movement and precision control.
Servo Motor Control → High precision, but more complex and expensive.

3. Integration with the Spin Coater

The system must be rigid enough to prevent vibrations.
Motion must be precise yet smooth to avoid uneven coating.

Next Steps in Slide System Development:

Test off-the-shelf linear rail systems to compare smoothness and precision.
Design a mounting system to attach the slide to the spin coater frame.
Evaluate stepper motor vs. manual control for better precision.

Conclusion & Next Steps

This week’s work has brought significant progress in:

Material selection for both transparent (lid) and structural (non-transparent) components of the spin coater.
Comparing key properties like heat resistance, impact strength, and machinability to optimize design choices.
Beginning research into a linear slide system to improve precision in the coating process.

Week 3

This week, I made significant progress on the CAD design for the automated spin coater system. A major focus was refining the structural framework, ensuring that it is both rigid and modular. The design utilizes aluminum extrusions, which provide a strong yet lightweight foundation while allowing for easy adjustments and scalability.

One of the key developments this week was the integration of a linear rail system at the base of the structure. This rail serves as the foundation for the horizontal motion of the spin coater platform. To achieve this, I designed a custom carriage system that allows the spin coater to move smoothly along the rail with minimal friction, ensuring the liquid on it isn’t affected by the motion. The carriage is designed to accommodate precise linear motion, which is essential for avoiding uneven coating application.

Additionally, I incorporated an infrared distance sensor into the design. This sensor will play a crucial role in detecting and monitoring the position of the spin coater platform, ensuring precise control over its movements. By providing real-time feedback, the sensor will help maintain consistency in the coating process, an essential factor for achieving reproducible results. The placement of the sensor was carefully chosen to maximize accuracy while minimizing interference from other components.

Beyond the core structural and motion system, I also worked on establishing a system for the CAD, including redesigning the 80/20 rail to be a bit simpler and work better in Onshape assemblies. While small, these changes make it monumentally easier for the team to design, and provide a standard that can be used in the future.

Moving forwards, my tasks will include designing the belting system used to drive the linear slides, as well as helping to design the element going on top of the cage, including the liquid handling system and the heat gun. Once these are accomplished, I have to test the spin-coater on the linear slides to determine what acceleration/ ramp-up is required to avoid messing up the liquid on the ASC.

Week 4

This week, I focused primarily on the project presentation for Tuesday. However, I also tested the IR sensor using an Arduino. This involved setting up the hardware on a breadbaord, writing the necessary Arduino code, and debugging any issues that arose during the process. A few issues arose with random jumps appearing the return values, but I discovered that this was due to a bad soldering connection. Next week, I should have all the parts necessary to begin building a first prototype of the linear slide mechanism, which I can also test with the new infrared.

Last updated 2 days ago