How to make nanofiber production a user-friendly process
It is possible to produce a simple electrospinning device with a minimal number of components. The heart of the device is an adjustable high-voltage source to which an emitter is connected to transmit high voltage to the polymer solution. The charged polymer strives to get to the nearest place with the lowest potential, such as to a grounded collector, usually 5 to 30 cm away.
Automatic Polymer Dosage
Automatic dosage with an accurately configured polymer supply is essential for the user-friendly production of nanofibers. However, securing an accurate and automatic dosage system in itself is not easy while considering what happens with a dosage drive in a 60 kV electric field. Inaccurate dosing is caused by using compressed air as a propellant due to the various viscosities of the polymers spun and air compressibility.
Hence, using plastics as insulators is the best option. 4SPIN has finally succeeded in finding a solution that deals with dosage very competently. Figure 1 shows a polymer dosing system with the use of a multi-needleless emitter.
Figure 1. Polymer dosing system with a multi-needleless emitter.
Spinning Chamber and Electrodes Replacement
Even though electrospinning can be done on a bench top, it is best to spin fibers in an adapted chamber. It is also possible to use a chamber to control factors such as temperature, humidity and air flow. 4SPIN offers fundamental operating safety with a transparent cylindrical chamber with sliding doors and a security lock. Figure 2 shows a cylindrical spinning chamber.
Figure 2. Cylindrical spinning chamber.
It is much easier to produce the chamber as a rectangle or a cube; however, the decision to reduce the number of corners and edges was obvious while considering the chamber space maintenance required to ensure improved electrospinning efficiency and clean production. The plastic cover is completely transparent so that the operator can monitor the spinning process and make adjustments as required. The automatic earthing of the high-voltage part implies that the operator is not delayed by manual discharge or at risk of a flat residual charge, making this feature a refreshing bonus.
Figure 3. Emitter E4 connecting plugs.
Control System for Controlled Spinning Process
In case one is monitoring different variables and it is required to be time efficient and ensure excellent accuracy, the control system cannot be avoided. The consistency, robustness and modularity of 4SPIN makes it the choice of the main control system taking care of the management of individual process variables.
Figure 4. Touch screen menu in “Basic options”.
The complete PLC program is written in a structured language so it can be used at any time on other such controllers where required. The most interesting element about the control process is the use of a PID (or PSD) control algorithm developed by Contipro and verified in stress tests.
Individual variables are quickly sped up by this algorithm to the required tolerances, including the settings of specific parameters of the components.
Another advantage of opting for the PLC is the saving settings in formulas (procedures) so that users can easily save/load process data and thus increase their productivity. This solution is required for repeatable laboratory tests or production. The final step is to make data available for remote monitoring via a Modbus protocol and thus through commonly available SCADA systems. The PC software written is just an example of what can be monitored.
How to Generate Nanomaterials Easily and Efficiently
4SPIN was developed not just to be used in an industry set-up but also in an academic setting where it will be operated by students following detailed training.
After logging in through the touch screen, users can set parameters to the recommended values, i.e. they can select a collector (or the speed of the rotational collector), emitter (or the air temperature during electroblowing), and the distance between electrodes, and adjust the air pressure, the voltage, the spinning time and the dosing rate.
The quality and structure of materials produced are affected by all such parameters. Major advantages here are that the parameters can be set quickly and the device itself monitors the consistency of the conditions.
Furthermore this device can produce nanofibers from biopolymers, which has previously proved difficult or impossible. It is also possible to align the fibers produced with a success rate of up to 97%. Also, for the most productive jet, the machine can deliver much more than just test samples. All this, along with the ability to install the device in a clean room, offers great potential for research into the development of new medical applications for nanomaterials.
Figure 5. Supplying terminals and the main switch to the electrospinning device 4SPIN.