Researchers from the University of Edinburgh have used FDM 3D printing to fabricate a low-cost electrospray/electrospinning device intended for biomedical applications.
Although leveraging different techniques, both electrospray and electrospinning methods use analogous technology for the production of nanostructures. Electrospinning enables the production of polycaprolactone fibers with diameters in the order of some hundred nanometers. Electrospray ionization (ESI) on the other hand is used to prepare nanospheres and nanoparticles. However a typical laboratory electrospinning setup can be capable of both the electrospray and electrospinning modes.
Part of the School of Engineering, Institute for Materials and Processes at the University of Edinburgh, the researchers identified that the commercial setup for electrospray and electrospinning methods can cost between $17,000 – $300,000 USD, despite being fairly simple to establish. As such, many researchers have resorted to unsafe, homemade solutions. As a potential answer, the researchers have developed and shared an FDM 3D printing process enabling the fabrication of a safe, modular electrospray/electrospinning setup.
What are electrospinning and electrospray techniques?
A fiber production method, electrospinning uses electric force to draw charged threads of polymer nano/micro-fibers. It is a widely used method for pharmaceutical, medicinal or biological applications such as scaffolds for tissue engineering or creating nanofibrous wound dressings. Explaining further, the researchers that “It is also widely used in medical diagnosis and drug delivery as they can immobilize the recognition element or active pharmaceutical ingredient due to the large surface area and porosity.”
The electrospray technique, also known as ESI, enables the production of ions, which are atoms or molecules with a net electrical charge. To achieve this, the technique leverages an electrospray to apply a high voltage to a liquid to create an aerosol. An electrospray itself is an apparatus that employs electricity to disperse a liquid. Electrosprayed nanoparticles are often used for pharmaceutical, biological or medicinal applications. For example, electrospray can be used to fabricate nanoparticles loaded with drugs for nanoparticle drug delivery or loaded with cell growth factors for tissue engineering.
Both methods make use of electrohydrodynamic mechanisms to fabricate nano/microparticles and nano/microfibers. As such, a combined setup can be made enabling the use of both techniques, with each mode depending on the viscosity and electrical conductivity of the solution. As described by the researchers in their study, a general setup would consist of “(i) a syringe, which is placed inside a syringe pump for continuous solution flow; (ii) a metallic nozzle; (iii) a high voltage power supply (which is connected to the nozzle); (iv) and a collector (which is conductive to attract the charged nanoparticles/nanofibers, and is placed opposite to the high voltage electrode).”
For both electrospinning and electrospray, the liquid that is ejected from the nozzle forms a specific cone geometry, called Taylor cone. In the electrospray mode, highly charged droplets are ejected from the Taylor cone, and upon solvent evaporation, solid nanoparticles can be collected. While in electrospinning mode, continuous fibers are emitted from the Taylor cone, and the nanofibers solidify after the complete solvent evaporation.
However, the researchers explain that commercial setups of electrospinning and electrospraying techniques are expensive despite being easy to create, and as such many researchers around the world are instead using home-built experimental setups, where the users can be exposed to electric shock from the high voltage components.
Establishing a safer, cheaper alternative with 3D printing
In response, the researchers have identified FDM 3D printing as a suitable and low-cost solution for fabricating an electrospray/electrospinning setup with similar reliability and reproducibility of the results as the commercial ones. In their research paper, they outline the creation of the setup in full, while also providing the files and parameters needed to print their device for free. Designed to be modular, its parts can be exchanged easily, and the design also provides a safe setup, ensuring that the users are not exposed to the high voltage parts.
PLA, PVA, and a thermoplastic elastomer filament were used to 3D print the devices on an Ultimaker 3 FDM system, materials costs were $100 USD. The 3D printed components consist of a nozzle holder, safety cap, central chamber parts, and the end part with internal gas channels.
Altogether, the electrospray/electrospinning setup was 3D printed in 6 days. Once completed, the researchers tested the device in both electrospray and electrospinning modes successfully, however they recommend that ABS, PEEK, or ceramic materials are used for 3D printing the central chamber part in order to increase the chemical resistivity.
Thus, the authors of the paper concluded that “3D printing offers a low-cost way to manufacture a safe and reliable experimental setup that is similar to the commercial ones. This paper presented a method for 3D printing a modular electrospray/electrospinning setup using an inexpensive FDM 3D printer […] The setup was tested in both electrospray and electrospinning modes successfully.”
Creating accessible medical devices
Various researchers have produced studies recently that look at different ways to leverage 3D printing in order to make certain medical devices more accessible.
For example, earlier this year researchers from the University of Granada, Spain, and the University of Glasgow, Scotland, used 3D printing to enable the diagnosis of parasitic infections using smartphones. This diagnosis can be achieved on the mobile phone using a 3D printed plastic accessory, which attaches to the smartphone camera and provides controlled illumination and fixed sample positioning.
By developing an accessible and affordable method for diagnosing these diseases, the researchers hope that it can be utilized in remote areas of developing countries that have limited access to resources for such tools.
3D printing has also been leveraged to build a standalone high-resolution digital holographic microscopy (DHM) microscope. Seeking to create a portable, powerful and cost-effective microscope, U.S. researchers 3D printed the device to enable the diagnosis of diseases like malaria, sickle cell disease, diabetes, and others.
The simplicity and low cost of constructing the instrument, which is made entirely from 3D printed parts and commonly found optical components, could “increase access to low-cost medical diagnostic testing,” according to research team leader Bahram Javidi from the University of Connecticut, which he claims “would be especially beneficial in developing parts of the world where there is limited access to health care and few high-tech diagnostic facilities.”
The research paper “Low-cost FDM 3D-printed modular electrospray/electrospinning setup for biomedical applications” is published in 3D Printing in Medicine. It is written by Jing Huang, Vasileios Koutsos and Norbert Radacsi.
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Featured image shows electrospray/electrospinning chamber CAD drawing with the rotating drum collector present. Image via 3D Printing in Medicine.