ElectrospinTech
Assembly of electrospinning setup for spinning of nonwoven fibrous membrane - Basic Setup
This work by ElectrospinTech is licensed under a Creative Commons Attribution 3.0 Unported License
Purpose
This standard describes the assembly of electrospinning setup from off-the-shelf apparatus. It includes the spinning of a test solution for training purpose.
Note: The procedure, apparatus, material and their specifications described in this standard are recommendation for beginners to electrospinning.
WARNING: High voltage used in electrospinning can result in serious injury if proper safety precautions are not taken.
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Disclaimer Any instruments and materials mentioned in this standard is for reference only. Electrospintech does not guarantee its availability or quality. This standard did not undergo formal peer review process and is for reference only. This standard does not address all safety and health issues regarding the performance of the experiment and/or the end product if any. It is the responsibility of the user to establish appropriate controls, safety and health practices. Local regulatory controls and limitation shall be addressed by the users of this standard prior to its use. |
1. Introduction
Electrospinning is a simple process used in the production of fibers generally in the range of hundreds of nanometers to the tens of microns although it has been demonstrated to spin fibers in the tens of nanometers. In a typical setup, the fibers are collected in the form of nonwoven membrane. Fibers and fibrous structure constructed using electrospinning has been used in a wide range of applications from tissue engineering, filter membrane to energy conversion and storage. To form fibers, the process uses repulsion between charges in an electrified solution to provide the force to extend a pendent drop of solution into fiber. The basic setup for this process will require a means of supplying electrical charges, a solution dispenser and a collector.
2. Equipment and consumables
2.1 Electrospinning setup components and consumables
| Description | Specification | Example |
| High voltage power supply | Voltage: 0 to 30 kV Current: 0.5 mA to 1.5 mA Note: Request for output cable Ensure there is an earth terminal on the instrument |
|
| Syringe pump |
Extrusion syringe pump Able to fit in syringe up to 20 ml |
|
| Hypothemic needle |
Gauge: 27G Preferable flat tip |
|
| Syringe |
5 ml plastic Luer lock (Do not use needle with slip-on design) |
|
| Alligator/crocodile clips | Quantity: 2 to 3 | |
| Extra wires for linking setup to earth terminal | ||
| *Adjustable jack | Quantity: 2 | |
| Aluminum foil | ||
| Voltmeter | Able to measure DC voltage up to 30 kV | |
| Office clip | Quantity: 4 | |
| Black Board | A3 size |
2.2 General lab equipment, PPE and consumables
| Description | Specification | Example |
| Glass bottle with cap | Volume: ~5 ml | |
| Magnetic stirring bar | 1 cm length | |
| Magnetic stirrer | ||
| Paper wipes | ||
| Pipette | Measure accurately to 4 ml | |
| Measuring scale | Measure to a precision of 3 decimal points | |
| *Optical Microscope | ||
| Lab coat | Long-sleeved | |
| Glove | ||
| Facemask | ||
| Goggles | Fully covered, chemical resistant |
2.3 Reagent
Note: Other solution may be tested once you are familiar with the process.| Polymer | Specification | Source |
| Polyvinyl pyrrolidone (PVP) | Mw 3.6 x 10e5 | Sigma Aldrich |
| Polyethylene oxide (PEO) | Mw 6.3 x 10e5 | Sigma Aldrich |
| Polyacrylamide (PAM, non-ionic) | Mw 3 x 10e6 | Yixing LVKE Environment Agent Co., Ltd in China |
| Polyacrylamide (PAM, anionic) | Mw 2 x 10e6 | Yixing LVKE Environment Agent Co., Ltd in China |
| Solvent | Specification | Source |
| Water | Not applicable | Not applicable |
| Polymer / Solvent | Specification | Source |
| PVP / Water | 16 wt% | Not applicable |
| PEO / Water | 8 wt% | Not applicable |
| PAM (anionic and non-ionic) / water | 20 wt% | Not applicable |
3. Procedures
3.1 Setting up high voltage power supply
Connect the output cable to the high voltage power supply. Attach a crocodile clip to the other end of the output cable. If the cable is too stiff, a short wire may be used as bridging connection between the output cable and the electrospinning needle.
WARNING: The electrical insulation of the bridging wire may be too thin to fully insulate the high votlage passing through the wire from the environment thus it should be kept as short as possible and away from other surfaces.
3.2 Assembling the electrospinning setup
The electrospinning setup assembly shall be located in a fumehood while the high voltage power supply should be placed outside with the high voltage output cable running into the fumehood deck.
TIP: Have a black board behind the electrospinning setup to faciliate visualization of the spinning jet.
If the frame of the fumehood is made out of metal, connect an earth wire using crocodile clip from the frame to the earth terminal on the high voltage power supply.
Place the syringe pump on a adjustable jack.
Cut out a piece of aluminum foil that can cover the surface of the jack. Use office clips to hold the foil to the jack surface.
Connect an earth wire (wire from the earth terminal of the high voltage power supply) from the aluminum foil using a crocodile clip.
Rest the jack on its side with the aluminum foil in the direction facing the syringe pump at a distance of 10 cm.
3.3 Solution preparation
Prepare about 4 ml of solution one day in advance.
Measure appropriate mass of the polymer powder and pour into a glass container.
Measure appropriate volume of water and pour into the glass container.
Use magnetic stirring bar to mix the solution on a magnetic stirrer.
3.4 Fiber spinning
WARNING: Ensure the high voltage power supply is switched off and the voltage is set to zero
Switch on the syringe pump and set the feedrate to 1 ml/h.
Transfer the solution into the syringe.
Screw in the needle and expel any air trapped in the syringe until a drop of solution is formed on the needle tip. Use paper wipes to clean off the solution droplet.
Note: By pointing the syringe tip skyward and squeezing out the air.
Place the syringe on the syringe pump and clip the crocodile clip which is connected to the high voltage power supply to the needle.
Switch on the syringe pump.
When a drop of solution emerges from the tip of the needle, switch on the high voltage power supply. Turn up the voltage until the solution drop starts to contort and a jet is observed to form at the tip. Generally, this voltage is about 6 kV and above depending on the solution.
Lower the fumehood sash to reduce exposure to aerosol and fibers.
Wait for a couple of minutes. White deposits should be seen on the aluminum foil.
NOTE: Extra precautions are required when spinning hazardous solution.
3.5 Examination of collected fiber
Switch on the blower of the fumehood.
Turn the voltage down to zero and switch off high voltage power supply.
Raise the fumehood sash.
Use the earthed wire (from the collector or connected to the fumehood) to touch the needle and the body of the syringe pump to ensure they are properly discharged.
Stop the syringe pump.
Remove the aluminum foil and examine the collected fiber under an optical microscope.
Repeat the procedure to continue spinning as necessary.
4. Storage
Residual or trace amount of solvent may still be present in the collected fibrous membrane. It is recommended that the membrane be kept in the fumehood with the blower switched on or other appropriate drying equipment for at least 24h to reduce exposure to the solvent coming from the membrane.
NOTE: Instruments like SEM and TEM are sensitive to the presence of solvents and vapors. Examination of collected membrane using such instruments should only be carried out after a day of drying.
5. Safety
5.1 Chemical safety
Consult the Material Safety Data Sheet (MSDS) provided by the chemical supplier or over the internet if you are unsure of any hazard posed by the chemical in use.
Preparation of solution especially involving hazardous substance must be carried out in the fumehood.
5.2 Personal protective equipment (PPE)
Full chemical resistant goggles to reduce exposure of the eye to solvent vapor, particles or fibers
Long sleeved laboratory coat to reduce exposure and contamination of skin and personal wear to spills, particles or fibers
Facemask to reduce exposure of the eye to solvent vapor, particles or fibers. For organic solvents, use half-mask (eg. 3M Half Facepiece Reusable respirator 7500 series) with cartridge that removes or adsorb organic solvents (eg. 3M Gas and Vapor Cartridge 6000 series).
Compatible gloves (latex, nitrile)
5.3 Electrospinning safety precaution
Do not touch the syringe pump, syringe, needle or the high voltage power cable with you hand when the power supply is switched on. If clogging of the needle tip occurs, either follow the procedure 3.5 to shut down the spinning process or use an insulated tool to remove the clog.
6. Disposal
WARNING: Most countries have strict regulation regarding proper disposal of chemicals especially toxic materials and solvents. In general, DO NOT pour unused solution containing down the sink if you are unsure of its safety.
Currently, there is no official warning regarding exposure to electrospun polymeric nanofibers. Thus routine disposal method for general lab constructs may be followed unless otherwise stipulated by local regulation.
Glass bottle used to contain solution for electrospinning should be left in the fumehood to dry (unless the solution is known to be non-toxic) before cleaning.
7. References
Sun GE, Teng H, Zhang C L, Dou Y L, Li Y. Preparation of Ultrafine Water-soluble Polymers Nanofiber Mats via Electrospinning. Chem. Res. Chinese Universities 2010; 26: 318.
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