Printable Electronics Reference Devices and Materials

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Revision as of 21:22, 21 September 2011 by Mrkim (talk | contribs) (Silver Ink:)
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Printable Electronics Reference Devices and Materials

Release status: Experimental

MrKim Sarik Printable Transistors part1-v1.3-1 2.jpg
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Printable Electronics Reference Devices and Materials
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Description:

This is a home for a set of reference devices and materials for printable electronics.

The Teflon Wick design for the Micron pen:

Sigma-micron-exploded-crop-800px.jpg
Micron-teflon-wick-v2.png
MrKim Sarik Printable Transistors part1-v1.3-32 2.jpg

Field Effect Transistor Patterns:

Gate layer

Dielectric layer

Semi-conductor layer

Source-Drain layer

Bistable Inverter:

Fet10bistableInvertersdgRoute.png

Materials:

There is a link between ease of printing and non-toxic materials


Silver Ink:

Features:

  • Water based
  • While printing it is pretty close to non-toxic. If the tool head touches you while printing you probably won't die.
  • cold valveless tool head
  • With the right particle size cure temperatures can be below plastic extrusion temps.

Design:
Previously, we demonstrated that sub-micron silver ink could be printed into circuits and active devices with a modified Micron pen. After printing, the ink particles were sintered on a hot plate to increase the conductivity.

The process worked well, but the ink was not readily available. Here is a possible method to fabricate the metallic ink. This would allow a cold process metal printing of circuits, devices and 3D structures.

Ionic Salt Crystals:
A metal and an acid can form an ionic salt that is water soluble.
The metal can be arranged in solution.
Then the salt can be reduced back into the metal with a reducing agent.
This might be a general way to deliver a range of metals via a water solution.
Or the particles can be reduced in the solution to yield a bunch of small particles. The colloid of particles would then be put in the pen.

Silver + Nitric Acid => Silver Nitrate(stains skin) + water + Nitrogen Oxide(a toxic gas)
3 Ag + 4 HNO3 → 3 AgNO3 + 2 H2O + NO

A solution of small silver particles can then be made by mixing the Silver Nitrate with a reducer such as Ascorbic Acid or Sodium Citrate. This transfers an electron back to the silver ion.

Silver Nitrate + Ascorbic Acid = Silver + DHA + Nitric Acid
2AgNO3 + C6H8O6 = 2Ag + C6H6O6 + 2HNO3.

To prevent the small particles from clumping or redisolving, a stabilizer or “capping agent” is added such as Polyacrylic Acid (PAA).
PAA + Diethanolamine(DEA) or polyvinylpyrrolidinone (PVP) or Sometimes a dispersing surfactant is used instead.

PAA is the absorbent powder in diapers and is listed as an irritant.

This solution is then heated mildly on a hot plate from 1hr to 24hrs.
I guess this is mainly for brownian motion.

Next, Ethanol(grain alcohol) which is less polar than water can be added to the water solution which will allow the particles to attract each other and precipitate out.

The particles can be further concentrated by spinning them.

Viscosity:
Viscosity increases with the concentration of particles. Solutions of 50% silver particles with a small amount of a viscosity additive were reported to have a viscosity of 0.1-1.0cP. Previously successful inkjet inks had a listed viscosity of 12 cP. Normal drawing inks are near the viscosity of water 0.894 cP.

So target concentrations of 50% silver particles by weight should work.

Notables:
Ink-jet fabrication of electronic components S M Bidoki, D M Lewis, M Clark, A Vakorov, P A Millner and D McGorman

NerdRage: Making Silver Nitrate

Pen-on-Paper Flexible Electronics Analisa Russo, Bok Yeop Ahn, Jacob J. Adams, Eric B. Duoss, Jennifer T. Bernhard, and Jennifer A. Lewis

Wikipedia Ethanol precipitation

Preparation and the mechanisms of formation of silver particles of different morphologies in homogeneous solutions, Lorenza Suber, Ivan Sondi, Egon Matijevic, Dan V. Goia

Commercial Organic Semi-Conductors:

P3HT

Zero Cost Organic Semiconductors:

Nature is full of amazing electrical phenomena!

The Class of Natural Pigments:
Beta-carotene
Mobility 4×10^(−4) cm^2/V/s
Number Check: 7 orders of magnitude lower than the electron mobility in silicon


Notables:

Lycopene has a striking resemblance to Polyacetylene and Beta-carotene.


http://www.nobelprize.org/nobel_prizes/chemistry/laureates/2000/public.html

Biocompatible-ingestible electronic circuits:
Biocompatible and Biodegradable Materials for Organic Field-Effect Transistors, by Mihai Irimia-Vladu

Dielectrics:

Art-store grade dielectrics are probably not going to be good enough.

Substrates:

Glass microscope slides

Resistor:

Graphite Pencil
Carbon particle "Wire Glue" ink.

Capacitor:

Surface Mount Motherboard Design for discrete components:

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Viewer-opengl-06-07-11.png

Components: Atmega1280