Welcome! We are Team #3 “Chickititos.” Yazmin, Ian, Caleb, and Fabian worked on this project during the Spring and Fall of 2023. Our project is titled “Nanogun.” The problem we tackled was nanofibers treatment for cuts and burns in hospital emergency rooms. We designed a portable device that generates and directs nanofibers onto a wound. We hope that you find this project as captivating as we did. Click on the Welcome Video below!

Play video button - Free interface icons

Team #3: Welcome Video

Back to INDEX.

WHAT IS THE PROBLEM WE ARE TRYING TO SOLVE?

Traditional wound dressings such as bandages and gauze are used to deal with minor and common wounds. However, more complicated or severe wounds can be difficult to treat - especially in situations that involve emergency first aid. Dealing with these injuries requires more intricate dressing methods that potentially cause discomfort or pain for the patient. The time it takes to deal with these injuries is also a very important factor.

We are proposing to create a handheld nanofiber device that can produce fibers that can be directly applied to an injury. Generally speaking, nanofibers aid in reaching hemostasis better than traditional wound dressings. This means that nanofibers stop blood flow better than bandages and gauze. The Nanogun creates a beam of fibers that can be pointed at an injury. This allows the fibers to stick to wounds or injuries better. This is also useful for treating diabetic wounds as they provide unconventional geometry that bandages and gauze cannot properly conform to.

Figure: The type of wounds the Nanogun aims to dress.

Back to INDEX.

IMPORTANT TO KNOW

To better understand the problem, we conducted background research on relevant topics. From this we learned the following:

· Nanofibers are beneficial for wound care treatment because of their physical characteristics.

· Nanofibers can pick up contaminants by slowing down blood flow and cleaning wounds.

· There are five different portable nanofiber products currently being researched around the world. These devices are all designed differently, some being shaped like a wand and others like a gun.

Electrospinning Machine by Qingzitech

· Due to the high surface-area to volume ratio, only a small layer of nanofibers is needed to function. In contrast, bandages and gauze make up a great deal of infectious biohazard waste. High-income countries generate 0.5 kg of hazardous waste per hospital bed per day, so any effort to minimize this should be investigated (“Health-Care Waste”).

· Nanofibers can be created through different methods – this project uses Forcespinning™. This involves spinning liquid solution - usually, a polymer and water or polymer and alcohol - inside a vessel with extremely small nozzles also known as spinnerets. Centrifugal force generated from spinning the spinneret causes the solution to shoot out and create an incredibly thin jet. The liquid then quickly evaporates and leaves the polymer behind as a fiber. There are other methods, but they have their pros and cons. Electrospinning takes a long time to make a large number of fibers. Blowspinning is done very quickly, but it produces a very small number of fibers.

Figure: Diagram showing different methods of nanofiber production.

Figure: Original “Toroid” design from previous teams.

· Airflow is generated with turbomachines (e.g. fans and blowers). Depending on their design, turbomachines favor generating a pressure difference or inducing volumetric flow rate. In simpler terms, turbomachines tend to either focus on creating a bigger pressure difference or in moving a greater amount of air.

Back to INDEX.

WHY IS THIS PROBLEM IMPORTANT?

There is a clear need for more comprehensive wound dressing methods that are both quick and robust. As previously mentioned, this is especially important for emergency first aid. The Nanogun is not only able to commercialize nanofibers, but also able to treat serious, and potentially life threatening, wounds. It bridges the gap between nanofibers, which have historically not had far-reaching appeal, and the need for better wound dressing methods. While there are other portable nanofiber devices, they pose serious drawbacks that either lack the speed or the scale of production necessary for widespread use.

Back to INDEX.

OUR PROPOSED SOLUTION

“We propose the design of a novel handheld mechanism that can generate nanofibers using centrifugal spinning as a method to address wound care efficiently to minimize wound infections. Additionally, this device would be able to produce nanofibers for different applications.”

After understanding the problem in depth, we explored various potential solutions and selected the best concept. This is how our proposed solution works: the Nanogun uses a battery that generates the power for a motor which will spin the spinneret and produce fibers through centrifugal spinning. Additionally, a turbomachine will generate airflow to allow Bernoulli’s principle to aid in the centrifugal spinning process.

We also wanted to design the inside of the Nanogun, as shown with the CAD below. This version of the Nanogun with varying cross-sectional area only uses the “Bullet” design as it helps reduce the wake created downstream of other spinnerets, such as the original “Toroid” design.

Nevertheless, our team designed different spinnerets to meet different design specifications. As previously mentioned, the “Toroid” design was inherited from a previous team. The “Spoiler” design will have an aerodynamic design that will use the rushing air to create a pressure difference. The “Bullet” design will minimize the impedance to the airflow, leading to a drastically reduced wake. The “Hybrid” design will optimize space by combining the functions of the fan and spinneret.

Back to INDEX.

FROM IDEA TO REALITY

The Nanogun has been a major passion project within UTRGV and has had a place as a senior design project for some years now. Because of this, there have been previous iterations of the Nanogun. The first iteration was large and functioned primarily as a tabletop design with the capability to attach a handle to it.

Figure: Back of Tabletop Design

Figure: Front of Tabletop Design

The second iteration then sought to further scale down the design so the Nanogun would be a dedicated handheld machine. However, this posed some serious problems that need to be addressed. These were some of the important design challenges and how we approached each one of them:

1. The electrical components must fit into the handle of the Nanogun

As our direct predecessors were not able to fit all the electrical components of the Nanogun into the handle, the shrinkage of the electrical components was a key design challenge. We have addressed this by using an Arduino uno and by using a small Lithium-Ion battery. We compared a plug-in design to a large Lithium-Ion battery and a small Lithium-Ion battery. While the plug-in design was very reliable, it lacks the portability needed for this project. The small Lithium-Ion battery was chosen as it can better fit into the handle of the handheld design.

2. Optimize fiber production

The Nanogun can produce nanofibers very quickly. However, the number of nanofibers produced is important for treating larger wounds. As nanofibers stuck to the inner barrel of the previous design, it is important to increase the number of usable nanofibers the Nanogun produces. To do this, we are proposing a coating or film for the inside of the barrel wall.

The team also compared various turbomachines. A compressor moves the least amount of air but does so at a very high pressure, fans move the most amount of air at a lower pressure, and blowers are a balance between the two. Without enough initial pressure, this pressure drop will be too low and create back pressure. Because of this, a turbomachine that both creates a pressure difference and generates airflow is needed. For these reasons, a blower was chosen.

3. Create a focused nanofiber beam

It is important to be able to precisely aim the fibers produced by the Nanogun to a patient's wound. This can be done by creating a smooth laminar flow and by reducing the exit size of the barrel. To meet these requirements, we compared a straight duct to a converging duct. It was decided that although a converging duct is harder to manufacture, it would prevent backflow and allow a more directed beam path.

4. Sanitation requirements

Sanitation is a crucial part in any biomedical setting. Because of this, the team compared a permanent, reusable spinneret, to a disposable one. A disposable spinneret was ultimately selected as keeping a reusable spinneret sterile and sanitary would be too difficult. In this way, a disposable spinneret would minimize the likelihood of outside contaminants being introduced to a wound and reduce the risk of infection.

Back to INDEX.

PROTOTYPE EARLY AND OFTEN

We found that physical prototyping was very helpful to increase our understanding of the problem and the feasibility of our solutions. Our first prototypes were simple but useful and we continued evolving into more complex ones.

This was our first prototype. It may be simple, but it helped us understand the size requirement for a handheld unit.

A machine with a wheel and wires

Description automatically generated

The design above was created by our faculty advisor, Mr. Potter. This iteration allowed us to test different spinnerets, as well as visualize our own prototype.

To test the spinnerets, an organized methodology was developed.

Figure: Solution made up of PVA and Water.

Firstly, an oil bath was set at 75°C and left on a stir plate. Then, PVA and water were weighed to create a 10 wt% PVA and 90 wt% water solution. Immediately after combining the PVA and water, the solution is left stirring with a magnetic stir bar in the oil bath for 1 to 1.5 hours. This concludes the solution prep.

Figure: Filling a syringe with the PVA and Water solution.

To fill the spinnerets, fill a syringe with 2 ml of the PVA-Water solution. Equally fill each chamber of the spinneret to avoid uneven rotation and, thus, vibrations. Secure the chambers with plugs or caps and attach the spinneret counterclockwise to the Nanogun’s motor mount. This prevents the spinneret’s rotation from unscrewing itself.

A screenshot of a computer

Description automatically generated

Figure: Experiment showing web of fibers produced from the Nanogun with Toroid spinneret.

Then, turn the motor on and spin from 4000 to 8000 RPM. A higher RPM will give a lower standard deviation for the fiber diameters. As the solution is drawn out, the solvent evaporates, leaving the PVA as strings or very thin fibers. Swab the area with tinfoil to collect fibers for further analysis.

Back to INDEX.

FINAL PRODUCT

Unfortunately, due to the confidential nature of the work done, the final product cannot be shown.

Back to INDEX.

FUTURE WORK

Although the Nanogun is fully functioning now with the innovations the team optimized, the work is never over. There are still some components that can be explored and optimized to improve fiber production. The most important of the future works would be optimizing spinneret production. Despite resin printing, the orifices are still liable to misprint possibly due to the resin being somewhat fluid while partially uncured. In most of the prints, the exit orifices were not printed properly, where only 2 or 3 of the 4 exits being fully functioning. Additionally, while a cleaning procedure was developed, improper cleaning can significantly impact the viability of the spinnerets. For these reasons, the manufacturing process of the spinnerets needs to be further explored with special consideration being placed in maintaining a controlled orifice size.

Producing a more controlled fiber beam is also a crucial future step. This will be done by 3D printing new nozzles to further aid in the placement of the nanofibers. This process needs to be an iterative approach, where different nozzle sizes must be tested to then find the critical area that the component can converge to. Aspect of the design process is part of the impedance matching that was explained during the SDI report to find the best operating conditions.

Lastly, further testing is required as the method used to produce nanofibers is vastly different from previous technology. This should be done to ensure that the Nanogun can generate nanofibers across distinct processing parameters, and to gain insight into the limitations of the Nanogun. These tests are theoretically infinite because they are incredibly dependent on the solutions which are produced. If the polymer or solvent is changed then the processing parameters will be completely different. Despite this, optimizing processing parameters for a base PVA-Water solution would allow for incorporation of additives with medicinal properties.

While the Nanogun is a success 10 years in the making, there is considerable work to be done. Not because of any failure or shortcoming but because a new technology has been produced. Just as Dr, Lozano’s Cyclone revolutionized the field of nanofibers by being more efficient than electrospinning, the Nanogun also holds this potential. Because of this, the team is also interested in investigating the viability of a patent. The Nanogun is the next step in commercializing nanofiber production and the team is incredibly honored to have been a part of this journey.

Back to INDEX.

IN CONCLUSION

This project ultimately leads us down to paths. First, for the straight duct, we found that we needed to need to continue exploring the hybrid and spoiler spinneret’s viability. However, for the converging duct, we must select an appropriate blower and experimentally plot the impedance functions when paired with the optimized spinneret. Thill will be done by comparing the experimental and computational fluid flow results.

Additionally, we found that a simpler approach to the spinneret design may prove more viable for shrinking down and minimizing turbulence.

Our Senior Design experience was insightful, both technically and in regard to teamwork. Halfway through the semester, Team #3 had a “State of the Union” meeting to discuss how each member was feeling and address the behaviors that could potentially lead to tension down the road.

Team #3 has also learned that it is best to play to each group member’s strengths and learn to embrace the roles and responsibilities that each member has natural strength towards.

Finally, we learned that different methods – theoretical, simulation, and experimental - are needed to have a balanced and sophisticated project. Holistic results should be verified through several avenues.

Back to INDEX.

REFERENCES

Bröte L, Gillquist J, Tärnvik A. Wound infections in general surgery. Wound contamination, rates

of infection and some consequences. Acta Chir Scand. 1976;142(2):99-106. PMID: 936945.

“Health-Care Waste.” World Health Organization, World Health Organization, https://www.who.int/news-room/fact-sheets/detail/health-care-waste.

Back to INDEX.

LEARN MORE ABOUT OUR DESIGN PROCESS

We went through a meticulous design process to arrive to the final solution. The information on this page is a summary intended for the public. To learn about the project details, contact Dr. Noe Vargas Hernandez at noe.vargas@utrgv.edu

Back to INDEX.

ACKNOWLEDGEMENTS

The team received help from various persons, their help was critical to our success, we would like to acknowledge:

Faculty Advisors: Mr. Gregory Potter, Dr. Karen Lozano, Dr. Victoria Padilla, and Dr. Javier Ortega

Teaching Crew: Dr. Noe Vargas and Mr. Gregory Potter

MECE Department: Dr. Robert Freeman, Ms. Thelma Castaneda, Ms. Annie Salinas, Dr. Jefferson Reinoza, PREM team, and Makerspace Staff!

Others: Pablo Vidal, Family, and Friends

We want to reiterate our thanks to Mr. Gregory Potter for his constant support and for giving us the chance to work on this project!

Back to INDEX.