Interview: How the US Army’s scientists are 3D printing Cyberpunk-style biological sensors 

“Conformal 3D printing enables the rapid and customizable fabrication of microfluidic devices on biological surfaces such as the human skin,” explains the CCDC Soldier Center’s Joshua Uzarski. “The ability to monitor a warfighter’s physical state could allow them to be safely removed from the field at a moment’s need, taking the judgment call out of the hands of the soldier.”

Fitting soldiers with biological monitoring devices might sound like something right out of Cyberpunk 2077, but using 3D printing, the US Army is fast-tracking the technology into 2020. The CCDC has developed novel multipurpose biosensors that, as well as physiologically tracking troops, have the potential to provide them with an enhanced awareness of situational threats in the field. 

As modern warfare becomes ever more advanced, the US Army has increasingly developed methods of protecting its personnel from the spectre of biological weapons. Utilizing the CCDC team’s 3D printed sensors, it could now be possible to detect weaponized toxins, bacteria or viruses on the battlefield, providing soldiers with the maximum possible chances of survival. 

Although several similar ‘lab-on-chip’ technologies have been trialled in recent years, Uzarski’s is the first to be developed into a fieldable device. Having led two other biosensor projects during his six years at the CCDC, Uzarkski is a specialist in surface chemistry, but since working with the University of Minnesota (UMN), he has made significant progress. 

Following the release of the joint-team’s paper, I held a Q&A with Uzarski and his CCDC colleagues Michael Wiederoder and Ruitao Su, to find out more about how 3D printing has made these implantable sensors possible. 

3D Printing Industry: What were the aims and ambitions of the CCDC’s research alongside UMN? 

Joshua Uzarski: The Soldier Center has worked on array-based biological sensors for a number of years, but did not have the capability to transition the discoveries into a fieldable platform. The UMN provided the engineering expertise to push microfluidic technology forward in a way that could help transition the sensor ideas into fieldable devices including textiles (for uniforms), portable field devices, and even on skin for physiological monitoring.

3D Printing Industry: What are the potential benefits of such devices within military applications?

JU: The benefits include the ability to create sensor devices that are more fieldable and compatible with biological based detection. Most current technology requires flat, stiff, and often heavy materials that do not translate to the field. These new types of devices can be created on soft, flexible, and light materials, such as textiles and the skin. 

Furthermore, their benign manufacturing conditions relative to prior techniques (such as high heat and harsh chemical treatments), and the elimination of supporting materials, permit the inclusion of sensitive biological molecules for sensor diagnostic tests. These include environmental observations for water quality and/or warfare agents, as well as physiological status monitoring.

3D Printing Industry: If used as a ‘lab-on-chip’ diagnostics tool, how would yours differ from those we’ve seen before?

JU: Several features of self-supporting microfluidics make it superior to previous methods when used for ‘lab-on-chip’ applications. Conventional devices typically require large slabs of cured polymers to encase the microfluidic channels, resulting in a bulky form-factor. By comparison, our 3D printed microfluidic sensors have a concise configuration, that consists of the sensing substrates and the 3D printed silicone channels. 

Our device doesn’t have strict cleanroom fabrication requirements either, such as the careful alignment of devices, which often requires more material, while providing limited multiplexing capabilities. The flexibility of our fabrication method also allows greater complexity to integrate 3D structures, multiplex arrays and multiple material types, than other lab-on-a-chip devices.

The researchers' 3D printed microfluidic devices have potential military monitoring applications. Gif via UMN.
The researchers’ 3D printed microfluidic devices could have potential military monitoring applications. Gif via UMN.

3D Printing Industry: What’s unique about your new additive manufacturing method and what are its advantages?

Our method is capable of designing the printing toolpaths according to the geometry of the target surface, and directly ‘write’ the microfluidic networks onto the surface. Conformal printing also enables the rapid and customizable fabrication of microfluidic devices on biological surfaces such as the human skin. 

Previous technologies, such as stereolithography (SLA) and inkjet printing, use UV-curable resins to create microfluidic chips, which are typically rigid after the materials are cured. By printing a highly elastic material like Room Temperature Vulcanizing (RTV) silicone, our method creates microfluidic structures that are flexible and stretchable, with a fracture strain up to about 350%. 

What’s more, because the structures are self-supporting, microfluidic devices can be directly aligned and printed on functionalized sensing arrays, leaving the sensing elements contamination-free. By contrast, microfluidic devices fabricated by other 3D printing methods, normally have the channels temporarily filled with residue resins or supporting materials, which will contaminate the sensing surfaces. 

Rapid prototyping techniques also allow shorter turnaround times than other microfluidic fabrication methods such as soft lithography with PDMS, machining or injection molding with plastics, and printing with paper substrates. This facilitates faster development to move towards real-world products and applications.

3D Printing Industry: What’s the potential of the technology you’ve developed, in particular within a military setting?

JU: The ability to have environmental and physical monitoring sensors with better performance and less warfighter burden, would provide much more and much faster information for situational awareness. For example, knowing that a water source is contaminated immediately without both carrying a heavy, power-hungry device in the field, while getting a fast response is a major potential breakthrough.

Further, the ability to monitor a warfighter’s physical state can have them safely removed from the field at the moment its need, also taking the judgment call out of the hands of the soldier. This new technology moves us forward towards those visions. Right now there is either impractical technology, or none at all, for these types of needs.

3D Printing Industry: Are there plans to continue in this area of research? If so, how could the technique be developed and enhanced further?

Right now on the military application side, there are research proposals in place to pursue using the technology for biological detection of specific toxins, bacteria, and viruses. This  will be modular, in that it could be pre-programmed later, and modified to detect different specific targets using pattern recognition responses. 

This technology could be leveraged to create future “on-demand” sensors, with all components printed rapidly in the field, to address threats of that specific environment. 

The researchers’ findings are detailed in their paper titled “3D printed self-supporting elastomeric structures for multifunctional microfluidics.” The study was co-authored by Ruitao Su, Jiaxuan Wen, Qun Su, Michael S. Wiederoder, Steven J. Koester, Joshua R. Uzarski and Michael C. McAlpine.  

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Featured image shows one of the researchers’ spherical 3D printed microfluidic devices. Photo via UMN.