We often cover the work of prolific Dr. Joshua Pearce, an Associate Professor of Materials Science & Engineering and Electrical & Computer Engineering at Michigan Technological University (Michigan Tech); he also runs the university’s Open Sustainability Technology (MOST) Research Group.
Dr. Pearce, a major proponent for sustainability and open source technology, has previously taught an undergraduate engineering course on how to build open source 3D printers, and four of his former students, in an effort to promote environmental sustainability in 3D printing, launched a business to manufacture and sell recycled and biodegradable filaments.In the past, Dr. Pearce has also researched syringe pumps, which are essential, but expensive, lab tools used to deliver drug doses and all kinds of other chemicals. A few years ago, he was the lead researcher on a project that developed an open source design for 3D printable syringe pumps, which cost far less to produce than traditional pumps. Now, Dr. Pearce has shared with us an interesting new Michigan Tech study that makes use of his 3D printable syringe pump in a 3D printer that’s been converted into a slot die system.
“Slot die coating is used to deposit a variety of liquid chemicals onto glass, stainless steel, or plastic substrates for the development and production of a broad range of applications such as: solar photovoltaic cells, flat panel displays (including LCD, OLED, and flexible), solid state lighting, and printed electronics sensors, RFID, fuel cells, and lithium ion batteries,” Dr. Pearce told 3DPrint.com.
The research team was able to make a slot die system, which would normally cost even a well-funded lab $4,000 due to complex machining costs, for just 25 cents out of a converted RepRap 3D printer – an astonishing 17,000% decrease in cost. Then, the researchers used their new system, with a 3D printed syringe pump, to print versatile wide band gap semiconductors using nickel oxide.
Dr. Pearce told 3DPrint.com, “This approach has all kinds of advantages besides costs: lower lead times, higher yields than competing technologies like spin coating, more customization, and the ability to scale up to roll to roll deposition if your hack works.”
The results of their case study have been detailed in a paper, titled “Open-source parametric 3-D printed slot die system for thin film semiconductor processing,” which was published in the Additive Manufacturing journal; co-authors include L.Y. Beeker, Adam M. Pringle, both of Michigan Tech’s Department o! Materials Science & Engineering, and Dr. Pearce.
The abstract reads:
“Slot die coating is growing in popularity because it is a low operational cost and easily scaled processing technique for depositing thin and uniform films rapidly, while minimizing material waste. The complex inner geometry of conventional slot dies require expensive machining that limits accessibility and experimentation. In order to overcome these issues this study follows an open hardware approach, which uses an open source 3-D printer to both fabricate the slot die and then to functionalize a 3-D slot die printing system. Polymer materials are tested and selected for compatibility with common solvents and used to fabricate a custom slot die head. This slot die is then integrated into a 3-D printer augmented with a syringe pump to form an additive manufacturing platform for thin film semiconductor devices. The full design of the slot die system is disclosed here using an open source license including software and operational protocols. This study demonstrates that functional lab-grade slot dies may be 3-D printed using low-cost open source hardware methods. A case study using NiO2 found an RMS value 0.486'¯nm, thickness of 17'“49'¯nm, and a maximum optical transmission of 99.1%, which shows this additive manufacturing approach to slot die depositions as well of fabrication is capable of producing viable layers of advanced electronic materials. Using this method, a cost savings of over 17,000% was obtained when compared to commercial slot die systems for laboratories.”