SPIE Photonics West in San Francisco always features the most exciting research in biomedical optics, biophotonics, industrial lasers, and is packed with presentations, exhibits, and the who’s who of optics and photonics tech. In this special “hot tech” section, we highlight exciting research, people, and technology shaping the future of the industry. Because he was originally scheduled but had to cancel at the last second, we caught up with Manuel Luitz, Ph.D. candidate and chair of process technology at NeptunLab.
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Q&A with Manuel Luitz, chair of process technology at NeptunLab.
Accumold: What are the most immediate applications of microstructured platinum in consumer and/or med tech?
Manuel Luitz: In the field of med-tech, I think one application could be the manufacturing of electrodes, e.g. for implants like the cochlea implant because platinum is biocompatible and a very good electrical conductor. These implants are generally quite small and by using 3D printing methods, the electrodes can be designed and tailored for each patient.
A different example for platinum microstructures which is more consumer tech can be found in the field of microelectromechanical systems (so-called MEMS), e.g. for temperature sensing, heating, flow sensing. Platinum has been successfully used in MEMS for these applications and simplifying the manufacturing process could open the door for many more applications. That way, scientists can try various geometries or patterns without having to go through a tedious and expensive manufacturing process.
Accumold: What previous challenges in microstructured platinum have prevented the technology from mass adoption?
Manuel Luitz: Platinum is usually microstructured by micromachining techniques. This is an established process which happens in a clean room, where a substrate, e.g. a silicon wafer, is coated with a photoresin. This photoresin layer is subsequently patterned with ultra violet light in the lithography step. Here the desired pattern of the platinum is basically transferred in this photoresin layer as grooves. After that step, a thin layer of platinum is sputtered on top of the whole substrate. Now, the metal is only in contact with the substrate in these previously manufactured grooves, the rest is on top of the photoresin layer. In the last step, the lift-off step, the photoresin layer is removed and only the desired platinum pattern from the lithography step remains. As you can see, this process involves many steps, is quite time consuming and requires a clean room facility. Additionally, this method only allows the manufacturing of 2.5 dimensional patterns and not 3 dimensional objects. 2.5 dimensional refers to a 2D pattern (let’s say in a x- and y-axis) which is pulled along the z-axis. That means overhangs or hollow objects are not possible.
Now, electrodes for a biomedical implants such as a cochlea implant can’t be manufactured in that way. Here we need free standing 3 dimensional objects. There are a few methods which allow the 3D manufacturing of platinum, but those require either very specialized and expensive equipment, or the manufacturing step is very slow, or the resulting platinum is not very pure and has many contaminants in it. Thus it’s not feasible for mass adoption. But this is also a 3D printing problem, which is not really suitable for mass production.
The processes that I developed for platinum microstructuring could speed this up. The first one is very similar to the micromachining technique which I mentioned in the beginning. However, in my process a lot of these steps are not necessary. I only need a thin layer of my developed platinum resin on top of a substrate, e.g. a glass slide, and then I can directly use ultraviolet light to pattern the platinum resin. After the patterning, I heat up the substrate to 600°C which in turn reduces the platinum salt in the photoresin to highly pure platinum.
In the 3D manufacturing approach, I use a similar platinum photoresin and use the high-resolution 3D printing system NanoOne from the company upnano. With this 2-photon lithography machine, the platinum photoresin is 3D structured and subsequently heated to 600°C as well, which transforms the printed polymeric object into highly pure platinum.
Accumold: What scalability limitations come to mind, and how do you adjust for those?
Manuel Luitz: By means of mass manufacturing, the 3D process by means of 2-photon polymerization is not suited for mass manufacturing. The devices become better and faster, which is incredible, but this technique, in my opinion, is a prototyping method. On the other hand, this technique is still quite new and who knows what scientists come up with to speed up this process even more.
The lithography-based approach could probably be scaled up, but so far I see it more as a laboratory method.
San Francisco Photo by Braden Collum