Open hardware and unconventional electronics John Sarik Columbia

Open hardware and unconventional electronics John Sarik Columbia University jcs 2160@columbia. edu

About me § I have a “distinct speaking style” § I’m a 5 th year EE Ph. D student at Columbia § Hardware hacker in the Columbia Laboratory for Unconventional Electronics - Led by Professor John Kymissis - Specialize in “novel integration” - Entrepreneurial emphasis • • Transistors Light emitters Photodetectors Solar cells • • Piezoelectrics Thin film batteries Strain sensors Actuators

What are unconventional electronics? § Conventional silicon electronics are following Moore’s Law and getting smaller and faster § Unconventional electronics are designed for applications with requirements that conventional electronics can’t meet - Unique sizes or shapes - Unique substrates - Unique mechanical, electrical, optical properties - Unique fabrication techniques § Unconventional electronics will compliment, not replace, conventional electronics

What is “novel integration”? § Energy Harvesting Active Networked Tags - Enabling technology for the “Internet of Things” § Lumiode: A high brightness, high efficiency microdisplay platform - Enabling technology for head-mounted, see-through augmented reality displays Silicon TFTs enable high performance circuits at low process temperatures III-V LEDs offer high optical power density, efficient light output, and long lifetime

What is open hardware? § “Open source hardware is hardware whose design is made publicly available so that anyone can study, modify, distribute, make, and sell the design or hardware based on that design. ” –OSHW Statement of Principles 1. 0

How open is open hardware? § Arduino, the most famous example of open hardware has an open source software tool chain, open source board design files, but non-open components Literal “black box”

Why is this a problem? § Philosophical - It’s a literal black box - The “I, Pencil” Problem § Practical - Limited selection of components and combinations of capabilities - Worldwide Atmel Shortage of 2011 - Counterfeit electronics are a growing problem

What’s the solution? § Replicators! - Rep. Rap is about making self-replicating machines, and making them freely available for the benefit of everyone. We are using 3 D printing to do this, but if you have other technologies that can copy themselves and that can be made freely available to all, then this is the place for you too.

What’s the state of the art today? § 3 D printers can print a wide range of materials at different size scales § Currently limited to printing mostly “structural” not “functional” materials

Can we print functional materials? § Yes! We can build unconventional electronics using conventional 2 D printing techniques

What else can we print? § Transistors § Solar cells § Batteries § Displays § Passives (resistors, capacitors) § The most fundamental printable component is a conductive trace!

How do we combine 2 D printing and 3 D printing? § Most hobbyist 3 D printers build objects layer by extruding thermoplastics, but there are currently no functional commercially available thermoplastics § Printing functional materials requires additional hardware! [1] Sells E. , Bowyer A. , 2004. Rapid Prototyped Electronic Circuits. http: //www. staff. bath. ac. uk/ensab/replicator/Downloads/RPEC-manual. doc [2] Bayless, J. , Chen, M. , and Dai, B. , 2010. Wire embedding 3 d printer. http: //www. reprap. org/mediawiki/images/2/25/Spool. Head_Final. Report. pdf [3] http: //openmaterials. org/2010/12/14/diy-printed-transistors-botacom/ Wire Extruder [1] Woods Metal [2] Silver Pen [3]

What are the current limitations? § Software - Currently limited to printing in a single plane - Existing software toolchain converts a 3 D model to a series of machine codes, but there is no standard for adding functional materials to a print - Need new file format (STL, Gcode, other? ) § Materials - Limited selection of compatible, available materials Air drying conductive inks Common Thermoplastics Extrusion Temp Acrylonitrile butadiene styrene (ABS) Polylactic acid (PLA) Polyvinyl alcohol (PVA) KOH Soluble Water Soluble 220 No No Cu. Pro-Cote (Cu) 195 Yes No Electrodag 915 (Ag) 180 Yes Conductivity (Ω/Sq@25 um) Price ($/m. L) Coverage (cm 2/m. L) 1 0. 10 137 0. 015 15 187

How do we combine 3 D printing and 3 D deposition? § Research conducted at Microsoft Research Cambridge in the Sensors and Devices Group § Spray deposition system based on a commercial airbrush and room temperature air drying conductive inks § Allows for easy conformal deposition of materials on non-planar, non-uniform surfaces

Overcoming the limitations of spray deposition § Object printed in ABS (red) § Sacrificial support and masking layer printed in PLA (blue) § Silver deposited (green) § PLA removed in KOH (ABS and silver not affected) § More complex structures can be fabricated by alternating between ABS, PLA, and silver § Excellent sidewall coverage allows truly three dimensional printed conductive trace

Immediate extensions § Fully additive, fully automated printed circuit board manufacturing § Printed electrometrical components

Future extensions § Explore new materials such as semiconducting, photovoltaic, or light-emitting inks § Improve the software toolchain and work toward a standard file format

What about stereolithography? § 3 D printers based on UV curable resins are becoming available § Similar to photolithography, a standard patterning technique for conventional electronics § Different wavelengths of light can be used to functionalize different materials

Can DIY electronics scale? § Traditional electronics fabrication requires extremely high yields § 3 D printed objects can fail in interesting and instructive ways § Printed electronics often fail in frustrating ways Thousands of transistors Millions of transistors

How can we bring printable electronics out of the lab? § Leverage the 3 D printing and open source communities § Bring together people with different areas of expertise

Conclusion § Printable electronics can enable truly open hardware (Turtles all the way down!) § OSCON attendees share a common vision of an open source future and have the skills necessary to make it happen Questions? Comments? Collaborations? § Email me at jcs 2160@columbia. edu Demos!