MIT Researchers 3D Print Electrospray Emitters for Wider Access

Researchers at the Massachusetts Institute of Technology (MIT) have developed low-cost 3D printed electrospray emitters, also known as triaxial electrospray emitters. These miniature electronic nozzles are designed to produce highly controlled microscopic droplets. In the past, devices of this kind typically required several days of fabrication inside expensive semiconductor cleanrooms, the same specialized facilities used to manufacture computer chips. By using 3D printing instead, the MIT team has introduced a faster and more accessible method that could make advanced electrospray technology easier to produce at scale.

Electrospray emitters are important because they can generate extremely small, uniform droplets with a high level of precision. A simple way to understand the process is to compare it with a spray bottle. A regular spray bottle uses physical pressure to push liquid through a small opening, creating a mist. An electrospray emitter performs a similar task, but at a much smaller scale and with the help of electricity. When high voltage is applied to a liquid flowing through a microscopic tip, electrical forces pull the liquid into a fine stream and break it into tiny droplets. This method can create droplets that are smaller, faster, and more consistent than those produced by traditional mechanical nozzles.

The Role of 3D Printing in Triaxial Emitter Production

The device created by the MIT researchers is especially notable because the team could not find previous reports of a miniaturized triaxial electrospray array in the open literature. The array measures about one square centimeter and contains a network of internal, coiled channels that feed 16 uniform nozzles. The word “triaxial” means that each nozzle includes three concentric nozzles nested inside one another. During operation, the device can eject three non-mixable liquids at the same time, forming a layered droplet with a controlled structure.

To fabricate the device, the researchers used vat photopolymerization with an Asiga Max X27 system. This 3D printing process allowed them to produce layers only 25 micrometers tall. With that level of precision, the team was able to manufacture helical microchannels that help maintain a steady and uniform spray of microdroplets across all nozzles. The channels also had to be designed without support structures, because any leftover support material could block the internal passages and prevent the device from working properly.

“We couldn’t make a device like this in a semiconductor cleanroom. This is only possible because they are 3D-printed,” said Luis Fernando Velásquez-García, a principal research scientist in MIT’s Microsystems Technology Laboratories (MTL) and senior author of the paper.

Another advantage of 3D printing was the speed with which the researchers could test and improve different designs. Instead of waiting through long cleanroom production cycles, the team could rapidly print new versions and study how changes in architecture affected the performance of the electrospray emitter array. They tested multiple designs to identify the best combination of liquid flow rates, nozzle geometry, and operating conditions for stable microdroplet production. “We were able to aggressively optimize the design because we could iterate in a much timelier manner. This ability to exquisitely refine designs is a key advantage of 3D printing,” Velásquez-García added.

According to MIT, one of the most important findings was that the viscosity of the middle liquid plays a major role in stabilizing the layered droplets. This middle layer helps preserve the thickness and structure of each droplet as it forms. The researchers also found that by adjusting flow rates and voltage, they could control the thickness of each layer within the microdroplet. This level of control is essential for applications that require predictable particle behavior and consistent material performance.

Applications in Drug Delivery and Biosensing

One of the most promising uses for 3D printed triaxial electrospray emitters is the production of three-layer drug-delivery nanoparticles. In a potential medical application, the outer layer of a particle could slowly erode in the stomach. A second material could then regulate the release of the inner core, which may carry medicine to a targeted area of the intestines. This kind of layered structure could help improve control over how and where active compounds are released inside the body.

During testing, the devices successfully generated uniform, three-layered droplets at scale. This uniformity is critical for high-throughput manufacturing, especially when the droplets are used to produce layered microparticles. Possible applications include biosensors designed to detect chemical substances, artificial cells for tissue regeneration research, and self-healing composite materials. In each case, consistent droplet size and structure can influence how reliable and effective the final particles become.

The MIT team plans to continue improving both the fabrication process and the design of the emitters. Future work may focus on achieving even smaller dimensions and integrating conductive or dielectric materials into the devices. These improvements could lead to more advanced electrospray emitter arrays with broader uses in biomedical engineering, advanced manufacturing, materials science, and microfluidics.

“The particles these devices generate, whether they are used for a self-healing composite or to deliver medicine, can have a big impact in many applications,” Velásquez-García added. By replacing traditional cleanroom-based manufacturing with precise 3D printing, the researchers have demonstrated a cost-effective route for producing electrospray emitters that are compact, complex, and scalable.

The research was funded in part by the Tecnológico de Monterrey – MIT Nanotechnology Program. Velásquez-García was joined on the paper by lead author Bryan Ivan Quintanar-Abarca of the Technological Institute of Monterrey in Mexico. The study was published in Virtual and Physical Prototyping.

*All Photo Credits: MIT