Climate control (temperature / humidifier and dehumidfier)

Overview

The electrospinning devices proposed by Inovenso. Ltd allows a high level of flexibility to tailor fiber’s specifications. The environmental parameters impact the morphology and characteristics of the nanofibers. The influence of relative humidity and temperature during the electrospinning process on the manipulation of electrospun nanofiber’s mechanical properties was widely investigated for different applications due to the impact on the performance and efficiency of the produced material.

Relative humidity plays an important role as an environmental parameter during the electrospinning process as well as temperature and atmospheric factors. The correlation between electrospun nanofiber’s diameters and relative humidity is explained by the rate of solvent evaporation, in which a difference of solvent vapor pressure and partial pressure inside the electrospinning chamber is a served as pulse for solvent volatilization, this gradient inversely increases with the relative humidity. 

The temperature-controlled chamber ensures that the environmental conditions are optimised and efficiently controlled to ensure high quality of nanofibers/nanoparticles and allows a fine tuning of the process to meet the required specifications and maintain a reproducibility, stability and reliability of the deposited product.

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  • EFFECT OF RELATIVE HUMIDITY ON ELECTROSPINNING
  1. low relative humidity: It can be explained that in a drier condition, the rate of solvent evaporation is increasing and leading to a high polymer concentration, increase of polymer viscosity and decreases the voltage stretching the polymer chains which causes a solidification of the solution at early stages. An optimum humidity then needs to be set to obtain higher stability and promote better fibers formation. The charge accumulation in this case is enhanced leading to a more fiber alignment.
  2.  Higher relative Humidity: the increase of moisture level in the electrospinning chamber leads slow solidification caused by difference in partial pressure of the used solvent and absorbance of fibers to more moisture causing swelling and altering mechanical properties. Beading and fiber’s irregularities are also obtained due to the lack of complete solidifications of the fibers before reaching the collector. The desired morphologies and characteristics are obtained after the right optimization of the humidity level. Charge accumulation is also affected by high level of humidity, an increase of the conductivity on the collector surface occurs leading to a dissipation of the electric field impacting the nanofibers deposition patterns.
  3. The control of the fiber’s morphology is impacted by an optimization of the solvent evaporation rate and bead-on-strings apparition during the capillary breakup of viscoelastic fluid. Control of the relative humidity of the electrospinning chamber, contributes to a variation in nanofibers diameters for the same polymer.Jan Pelipenko, Julijana Kristl, Biljana Janković, Saša Baumgartner, Petra Kocbek, The impact of relative humidity during electrospinning on the morphology and mechanical properties of nanofibers, International
  • BENEFITS OF INTEGRATING HUMIDITY CONTROL SYSTEMS:

Several benefits can be obtained when using environmental control systems like humidifier and dehumidifier in the electrospinning systems, enhancing the quality and efficiency of the process and final obtained membrane. Here are some key advantages:

  • Improved fiber’s quality and membrane performance

Maintaining optimal humidity leads keeping nanofiber’s uniformity along the process and stability of the diameter’s morphology highly required for precise specifications. Also, a reduced beading is observed in an optimum level of humidity with smoother nanofibers surface.

  • Higher mechanical properties obtained

Controlling the relative humidity also has an important impact on mechanical properties including strength and flexibility of the fibers with consistent performance with improving reliability of the final membrane.

  • Optimal solvent evaporation

By controlling the relative humidity of the chamber, an efficient solvent evaporation rate occurs leading to ensure fiber solidification in the right time with the aimed structure with reduce of materials wastes.

  • Electrospinning process stability

Stable and consistent humidity level during the electrospinning process leads to reproducible results, easy to scale up for an industrial level and commercialization applications with reduced variability and fluctuations in fiber’s quality.

  • Increase of the versatility of electrospinning process

The versatility obtained by humidity controls gives the opportunity to test and explore a large scale of polymers and blends for innovative materials with unique properties. 

  • Economic optimization

A high-cost efficiency is calculated by improving fiber’s quality, reducing wastes and optimizing materials uses with enhancing the productivity and stability of the process. Also, this stability and scalability leads to a time saving and reduced troubleshoot occurring or post-processing.

Pelipenko, J., Kristl, J., Janković, B., Baumgartner, S., & Kocbek, P. (2013). The impact of relative humidity during electrospinning on the morphology and mechanical properties of nanofibers. International journal of pharmaceutics, 456(1), 125-134.  https://doi.org/10.1016/j.ijpharm.2013.07.078

 Gao, 

X., Wen, S., Yang, B., Xue, J., & Wang, H. (2020). Enhanced air filtration performance under high-humidity condition through electrospun membranes with optimized structure. Chinese Journal of Chemical Engineering, 28(7), 1788-1795. https://doi.org/10.1016/j.cjche.2020.02.025 

 

    • EFFECT OF TEMPERATURE-CONTROLLED CHAMBER IN ELECTROSPINNING

    The major challenge in the electrospinning/electrospraying is the parameter’s control and safety features due to the use of toxic solvents and environmental controls for a stable fibers and particles production. One of the main parameters impacting the quality of the process is the temperature (T) in the deposition chamber.

    A proper control of the temperature during the nanofibers and nanoparticles formation is very crucial in the solvent evaporation rate and affects the general stability of Taylor cones and homogeneous structure of the deposited fiber. Uncontrolled ambient parameters affect the morphological and mechanical properties of electrospun nanofibers and electrosprayed nanoparticles, however with the controlled chamber, an accurate temperature is maintained to assure the continuous and stable production .

    The chamber designed by Inovenso Ltd  is assisting researchers and users by providing higher process stability (with a heating of spinning area up to 40°C) due to homogeneous charge dissipation which minimises structure variations  and prevent also the apparition and formation of defects in electrospinning such as beading, bundles, bonding (fiber to fiber) or a combination of defects in the same sample, a lack of uniformity in the nanofibers/nanoparticles and agglomeration can be observed during the electrospraying process if the temperature is not well controlled. Defect free structures lead to a high performance and reproducible nanostructures efficiently converged into the aimed application.

    • Importance of Temperature-controlled chamber:

    Phase separation: the temperature control is important in the case of polymer blend are used to control the phase separation during the process of deposition for an enhanced quality of the fibers/Particle’s uniformity.

    Solvent evaporation rate: adjusting a suitable temperature on the used solvent influence directly its evaporation rate from the deposited fiber/nanoparticle and lead to a stable jet and uniform morphology, uncontrolled evaporation led to discontinuation or an incomplete fiber/particle deposition during the process of electrospinning/electrospraying.

    Process stability: The fluctuation of the temperature during the process of electrospinning/electrospraying reduces the stability and continuous producibility of the deposited product with high occurrences of defects and inconsistencies.

    Nanofibers/nanoparticles morphology: adjusting a suitable temperature is directly correlated with the diameter of the produced nanofiber/nanoparticle, for instance, adjusting an optimal temperature can lead to a formation of thinner nanofibers and smaller nanoparticles with higher surface stability.

    • Advantages of the Inovenso’s designed temperature-controlled chamber:

    1- Increasing the process efficiency and avoiding production interruption caused mainly by clogging (caused by low boiling solvent). 

    2- Higher quality of samples and stability of reproducibility. 

    3- process scalability for a large production rate.

 

Journal of Pharmaceutics, Volume 456, Issue 1, 2013,Pages 125-134, ISSN 0378-5173, https://doi.org/10.1016/j.ijpharm.2013.07.078

 Kuzminykh, Y., Dabirian, A., Reinke, M., & Hoffmann, P. (2013). High vacuum chemical vapour deposition of oxides:: A review of technique development and precursor selection. Surface and coatings technology, 230, 13-21.