Make skew in rubbing durations - to find optimal durations to give nanospheres to deposition and adhesion one to another

Not continues movement of gear. Move and stop and then move and stop (in pulses).

Do the process with one size\different sizes of nano spheres.

Conduct thorough research and testing specifically focused on the compatibility of sputtering and coating processes with polystyrene nanospheres

Ensure that big and small particles distributed equally. Mix them before rubbing.

Change temperature to ensure good diffusion. The sample and the equipment can be heat with hot air.

Add to the nanospheres ethanol or material that decrease surface tension.

This project involves the study of polyspherene nanospheres deposited on PDMS (Polydimethylsiloxane) samples. The PDMS samples have undergone a mechanical rubbing process for various durations to create surface patterns. Following this, the samples were subjected to a sputtering process in a clean room environment to coat them with polyspherene nanospheres.

The primary objective of the project is to achieve a dense and uniform layer of polyspherene nanospheres on the PDMS substrates. This dense coating is crucial for the intended applications of these nanospheres in fields such as nanoelectronics, biomedical devices, and surface coatings.

Despite the systematic approach, the SEM (Scanning Electron Microscope) images reveal that the polyspherene nanospheres are not achieving the desired dense packing. Instead, the nanospheres appear to be sparsely distributed, with noticeable gaps between them, which undermines the effectiveness and uniformity required for their applications.

Improvement of Polystyrene Nano-Spheres Density and Uniformity of Mechanical Organization on PDMS Substrates

Lotem Kitaroo and Sharon Luzky

Solving problems and innovations in chemical processes

Improvement of Polystyrene Nano-Spheres Density and Uniformity of Mechanical Organization on PDMS Substrates

Lotem Kitaroo and Sharon Luzky

Force exercised on a unit area.  Stress is the effect of forces on an object.  Stresses can be tensile or compressive, static or dynamic.  The parameter also includes strain – provided length is not the main issue, in which case Parameters 3 or 4 should be used.

Stress, pressure

Universality

Preliminary action

Parameter changes

Component: Gear

Anything related to the cubic measure of space occupied by an object or the space around it.   'Moving' includes any situations where there is any degree of relative motion or mobility between two or more parts related to the problem.  This relative motion may be a few microns or a considerable distance.

Volume of moving object

Insufficient research or testing on the compatibility of sputtering process with polystyrene nanospheres

The energy and dynamics involved in the sputtering process may not be appropriate for depositing delicate materials like polystyrene nanospheres, leading to uneven deposition and structural changes.

sputtering can cause issues like non-uniform distribution and potential shrinkage of the nanospheres.

Sputtering method being used may not be suitable for achieving dense packing of polystyrene nanospheres.

SEM images reveal that the nanospheres are sparsely distributed with noticeable gaps between them.

Implement a pre-treatment step for the substrate to enhance adhesion and uniformity of deposition.

Utilize a different deposition technique, such as spin coating, to achieve a more consistent and even layer of nanospheres.

Investigate and implement a different sputtering method that is known to be more effective for achieving dense packing of polystyrene nanospheres.

Explore alternative deposition techniques such as drop-casting or inkjet printing to achieve a more uniform arrangement of the nanospheres on the substrate.

Conduct thorough research and testing specifically focused on the compatibility of sputtering process with polystyrene nanospheres

Custom Substrates: Preparing substrates using materials like polydimethylsiloxane (PDMS) provides a stable platform with suitable surface properties that facilitate uniform rubbing and distribution of nanospheres. The curing conditions and surface energy of the PDMS can be tailored to improve nanosphere alignment and reduce defects.

Optimizing Rubbing Duration: Experimentation with different rubbing durations (e.g., 6 minutes vs. 25 minutes) has shown variations in the clustering and distribution of nanospheres. Shorter rubbing times tend to form smaller, more stable clusters with less variation, while longer rubbing times can increase cluster sizes and uniformity. This indicates that optimizing the rubbing duration can help control the size distribution and uniformity of the nanosphere patterns.

Statistical Analysis -
Utilizing Scanning Electron Microscopy (SEM) for high-resolution imaging facilitates the analysis of the spatial arrangement and packing behavior of nanospheres of varying sizes. By employing image analysis algorithms, such as those in OpenCV, it is possible to detect, measure, and cluster nanospheres based on their sizes, enabling a detailed understanding of their distribution patterns. Additionally, other image analysis algorithms should be employed on the same results to allow for comparative analysis

Deposition Methods - Given the challenges observed with achieving dense and uniform packing of polystyrene nanospheres using sputtering, it is worth considering alternative deposition methods such as Thermal Evaporation or Vapor Phase Transport (VPT).

Sputtering Conditions - Adjusting the sputtering parameters (e.g., duration, pressure, and material deposition rate) to optimize the density of nanosphere coverage.

Mechanical Rubbing Process - The unidirectional rubbing technique is used to align and distribute nanospheres uniformly. This method involves controlled friction where nanospheres are rubbed between two surfaces, leading to their alignment and assembly in a specific pattern. Adjusting parameters such as rubbing speed, time, pressure, and substrate surface energy can help achieve a more uniform distribution.

Mixing Nanospheres with Different Sizes: Mixing nanospheres of different sizes before the rubbing process can improve packing density and reduce irregularities. Smaller nanospheres can fill the interstitial spaces between larger ones, leading to a denser and more uniform arrangement.

The system being analyzed in the solution is focused on the mechanical organization and distribution of polystyrene nanospheres with varying sizes on a polydimethylsiloxane (PDMS) substrate using a mechanical rubbing process.&nbsp;The main components and processes of the system include: 1. Polystyrene Nanospheres-Materials: Polystyrene nanospheres with specific diameters (e.g., 0.35 µm and 0.5 µm).Preparation: The nanospheres are prepared in dry powder form by mixing solutions of different sizes, centrifuging to remove liquid, and drying the resultant powder. 2. Polydimethylsiloxane (PDMS) Substrate-Materials: Silicone elastomer base mixed with a cross-linker.Preparation: The mixture is degassed under vacuum and cured at 60°C to form a solid elastomeric material. PDMS pieces are cut to fit into the rubbing machine and to match the size of the model holders. 3. Rubbing Process-Polystyrene powder is sprinkled onto the PDMS substrate.Smaller PDMS circles (1” diameter) are attached to the model holders, and a larger PDMS piece (8” diameter) is placed on the stage of the rubbing machine.The rubbing machine operates at 30 RPM, with experiments conducted for different durations (e.g., 6 minutes and 25 minutes).The machine combines rotational and translational motion to ensure uniform rubbing and avoid the formation of a second layer. 4. SEM Imaging-Samples are placed in the SEM chamber.High-resolution images are captured to assess nanosphere distribution, arrangement, and uniformity. 5. Image Analysis using OpenCV-Detects circular features representing nanospheres.Differentiates between large and small nanospheres based on radii.Identifies clusters and calculates statistical metrics such as cluster size and distribution patterns.

Improve the surface preparation of PDMS to achieve a dense and uniform layer of polystyrene nanospheres.

Mechanical Rubbing of PDMS

The system aims to achieve a uniformly coated PDMS substrate with polystyrene nanospheres through a sputtering process. This process involves several components and subsystems that work together to deposit nanospheres onto the PDMS substrate uniformly. The primary product of this system is a PDMS substrate that is densely and uniformly coated with polystyrene nanospheres, suitable for applications in nanoelectronics, biomedical devices, and surface coatings.

Sputtering with Polystyrene Nanospheres.

SEM Imaging of Samples. - The system involves imaging polystyrene nanospheres deposited on PDMS substrates using SEM.

SEM Imaging of Samples and Image Processing and Analysis

Process Overview-<ul><li>Objective: Achieve a dense and uniform layer of polystyrene nanospheres on PDMS substrates.</li><li>Steps: Mechanical rubbing of PDMS, sputtering with nanospheres, SEM imaging, and image analysis.</li></ul>Problem Statement- 			Despite systematic processing, SEM images show sparse and uneven distribution of nanospheres.

Improvement of Polystyrene Nano-Spheres Density and Uniformity of Mechanical Organization on PDMS Substrates Lotem Kitaroo and Sharon Luzky