Printed Electronics card with piezo-powered indicator

I came across a recently granted patent that describes a printed card such as a business card with a display that is powered by a built-in piezo power source. This is a neat printed electronics application that gets around the problem of needing a battery to operate any device such as an indicator or display printed on the substrate. Although there are “printed electronics” batteries they tend to require encapsulated electrolytes to fabricate them and so are not entirely compatible with low-cost printing processes.

The patent is US8959734 and was published on 24th Feb 2015. It has a priority date of 16th Dec 2010. Details of the inventors and assignee are summarised below along with the abstract:

Inventors: Daniel; Jurgen H. (San Francisco, CA), Ng; Tse Nga (Mountain View, CA)

Assignee: Palo Alto Research Center Incorporated (Palo Alto, CA)

Abstract

An interactive card or the like employs a piezoelectric charge generator (piezo-strip) for temporarily driving an indicator. The piezo-strip may be displaced (bent) in order to generate charge to drive the indicator. Printed electronic processes are utilized to produce the indicator and/or the piezoelectric charge generator. An indicator is formed on a substrate by way of a printed electronics process. A displaceable region of piezoelectric material associated with the said substrate is formed by way of a printed electronics process. Electrical interconnections are formed on said substrate by way of a printed electronics process. The electrical interconnections connecting said indicator and said first region of piezoelectric material such that displacement of said first region of piezoelectric material generates a voltage therein that is provided to said indicator in order to actuate said indicator and thereby indicate the displacement of said first region of piezoelectric material.

The drawings give a pretty good idea of the invention and its construction. I’ve reproduced two sets of figures below to show this but there are more in the patent that you can view.

Fig1_Fig2 Fig5_Fig6

FIG. 1 is an illustration of a display-capable business card with piezo-strip according to an embodiment of the present disclosure.

FIG. 2 is an illustration of the display-capable business card with piezo-strip according to FIG. 1, showing the deflection of the piezo-strip and the resulting actuation of an indicator.

FIG. 5 is a photograph of a display-capable business card with piezo-strip and template over an indicator according to another embodiment of the present disclosure.

FIG. 6 is a photograph of the components of the display-capable business card with piezo-strip and template over an indicator shown in FIG. 5.

Claim 1 provides the legal statement that defines the invention:

1. A method of forming an interactive card with indicator on a substrate, comprising: forming said indicator on said substrate by way of a printed electronics process; forming a displaceable region of piezoelectric material associated with said substrate by way of a printed electronics process; forming electrical interconnections on said substrate connecting said indicator and said first region of piezoelectric material such that displacement of said first region of piezoelectric material generates a voltage therein that is provided to said indicator in order to actuate said indicator and thereby indicate the displacement of said first region of piezoelectric material, said electrical interconnections formed by way of a printed electronics process, wherein said first region of piezoelectric material is formed over a piezo-strip region of said substrate; and partially disconnecting said piezo-strip region from said substrate in order to permit displacement of said piezo-strip region independently from the remainder of said substrate.

Phil’s comments:

Piezo technology does offer quite a few opportunities for where a brief amount of power is required to trigger a device. This patent describes one use illustrated above but also extends the ideas to other applications such as switches or sensors that can indicate if vibration or bending has happened. Another application detects liquid levels by sensing where the liquid moves a series of vertical flaps on the sensor by its swirling action. I have not seen any commercial applications of this but am aware of a Swiss company that uses the piezo effect to produce a keyboard and they recently demonstrated this integrated with one of Plastic Logic’s electrophoretic displays (see here).

Aqueous Conductive Silver Ink

Printed electronics is continuing to grow as more and more applications are developed and commercialised.  One of the key stumbling blocks continues to be the practicalities of printing narrow conductive tracks and the ease of use of the materials and processes involved.  One of the key system components, often taken for granted,  is the ink.  The majority of conductive ink compositions in use today are solvent-based thick film systems designed for low speed screen printing.  Water based conductive inks and coatings offer significant ecological advantages over solvent-based compositions, as the latter release solvents into the atmosphere on drying.  Aqueous conductive inks, however, have so far not offered the high conductivity, or low electrical resistivity, achievable with solvent-based formulas.

Sun Chemical Corp. have just been granted a patent for an aqueous ink with high conductivity and good printing properties.  This invention more specifically relates to an aqueous conductive silver ink suitable for use in RFID and other electronic technologies. The composition is highly conductive and requires reduced drying energy. In addition, it may be applied to low cost substrates via high speed printing processes. The key components of the ink formulation include: (meth)acrylic copolymer or salt thereof; conductive particles; an anionic surface wetting agent; defoamer and water.  The first claim suggests the ink can be up to 80% water depending on the amount of the other ingredients.

The patent is US8709288 and it was issued on 29 April 2014.  The Inventors are Jason Rouse and Dave Klein.

The independent claims from the patent are listed below:

1. A method of forming a conductive pattern on a substrate comprising applying a conductive composition comprising (a) metallic silver conductive particles, (b) water soluble styrene/(meth)acrylic copolymer, (c) an anionic wetting agent, (d) defoamer and (e) 10 to 80% water, the composition providing a sheet resistance of less than 0.83 ohms/sq, on the substrate and drying the composition.
34. A method of forming a conductive pattern on a substrate comprising applying a conductive composition consisting essentially of (a) metallic silver conductive particles, (b) water soluble styrene/(meth)acrylic copolymer, (c) an anionic surfactant, (d) defoamer and (e) 10 to 80% water, the composition providing a sheet resistance of less than 0.83 ohms/sq, on the substrate and drying the composition.
37. A method of forming a conductive pattern on a substrate comprising applying a conductive composition consisting of (a) metallic conductive particles, (b) water soluble styrene/(meth)acrylic copolymer, (c) an anionic surfactant, (d) defoamer, (e) 10 to 80% water, and optionally another solvent, the composition providing a sheet resistance of less than 0.83 ohms/sq, on the substrate and drying the composition.

The differences above are subtle but important, claim 34 describes the composition with an anionic surfactant rather than a wetting agent, and claim 37 describes a more general formulation with any metallic conductive particle and optionally includes another solvent.  Each claim includes the requirement that the composition provides a resistance of less that 0.83 ohms/sq on the substrate.

 

Phil’s Comments:

Good to see that research into inks suitable for printed electronics is providing environmentally acceptable formulations.  Reducing solvents and also reducing the energy requirements for drying are all good directions for the ink design.  We sometimes forget the huge demand put upon the inks we use, for example they need good abrasion and chemical resistance when dried so that they are not easily scratched or wiped off during subsequent uses, they need to have proper rheology and substrate wetting properties to obtain good ink transfer and graphic reproduction. Additionally, the ink should possess good flexibility and thermal stability to withstand the physical deformation to which the substrate may be subjected.  Let’s remember the research that goes into the inks when we next see a printed electronics design in use!

 

“Thinking Ink” – allows printed packaging to interact with smartphones

A recent patent lawsuit filed by Touchpac Holdings against TouchBase Technologies Inc. has highlighted the US Patent US8497850 which is owned by Printechnologics GmbH (T+Ink).  Details of the lawsuit were reported by Printed Electronics World in their article on 18 Feb 2014.

The patent was granted on 30 July 2013 and describes the technology that T+Ink have developed and called Touchcode.  This is a highly secure printed conductive ink signature embedded in packaging, labels and other objects that a smartphone or other sensing device can detect through capacitive touch.  The patent provides some detail of the system which is defined in independent claim 22:

A system comprising: a. an information carrier comprising a dielectric and/or conductive pattern which encodes information, and wherein the information carrier (1) comprises a substrate (2) with a first dielectric coefficient ∈1 and a second material with a second dielectric coefficient ∈2, the second coefficient ∈2 being different from the first coefficient ∈1, or wherein the information carrier (1) comprises a substrate (2) with a first conductivity σ1 and a second material with a second conductivity σ2, the second conductivity σ2 being different from the first conductivity σ1, b. a detection device having a capacitive touch screen; the detection device decodes the information upon interaction between the information carrier and the touch screen, wherein the interaction is based on a difference in the dielectric coefficient and/or the conductivity of the pattern, wherein the interaction is induced by relative motion between the information carrier and the touch screen.

A more visual explanation can be found on the T+Ink Touchcode website.  As explained on the website, Touchcode is an invisible electronic code printed on paper, cardboard, film or labels. Just put the product on the display of your smartphone/tablet/multitouch device to read the data.  In this way you can add interactivity to just about any product.  The system is similar to QR codes, barcodes or other tags but does not require activating a camera app on the phone or tablet to work.

Metal Nanoparticle Conductive inks Patented by Aculon Inc

Aculon Inc. were granted a patent on 15 October for “Electroconductive Inks made with Metallic Nanoparticles”.  Aculon are well known for their surface coatings using nanoparticle technology, featuring improved adhesion to a wide range of surfaces and adding functionality for numerous applications including printed electronics.  It is therefore no surprise that conductive inks are described with advantageous adhesion to a variety of substrates including silicon, glass and plastic.

The granted patent is US8558117 and the claims are quite broad but require the inks to have an omega substituted organophosphoric acid, this is the added ingredient which helps to improve the adhesion.

The first 10 claims are shown below:

What is claimed is: 1. An electroconductive ink comprising: (a) a dispersion of metal nanoparticles with a dispersant on the surface of the metal nanoparticles and as a separate component, (b) an omega substituted organophosphorus acid; the metal nanoparticles being present in amounts of 5 to 80 percent by weight and the omega substituted organophosphorus acid being present in amounts of 0.0005 to 5 percent by weight; the percentages by weight being based on total weight of the electroconductive ink.

2. The composition of claim 1 in which the metal is selected from copper, silver, palladium, gold or any combination thereof.

3. The composition of claim 2 in which the metal is silver.

4. The composition of claim 3 in which the dispersant is an organic carboxylic acid.

5. The composition of claim 4 in which the organocarboxylic acid contains from 4 to 36 carbon atoms.

6. The composition of claim 1 in which the metal nanoparticles have a particle size of 1 to 500 nanometers.

7. The composition of claim 1 in which the dispersion contains an organic diluent.

8. The composition of claim 7 in which the organic diluent is selected from hydrocarbons, alcohols, esters and ketones.

9. The composition of claim 1 in which the organo groups of the organophosphorus acid have omega substituted functional groups.

10. The composition of claim 1 in which the omega substituted functional groups are selected from phosphonic acid, carboxylic acid, hydroxyl, thiol and amine including various combinations thereof.

Phil’s Comments:

I have reported on a number of conductive ink patents over the past year or two and a common theme running through them is the need for good adhesion along with their conductivity.  The patents generally differ in the description of the adhesion promoting substances used in the nanoparticle inks and on other improved properties that enhance their application for printed electronics.  Successful conductive ink formulations are essential for printed electronics to become a mainstream technology for building new devices and specialist inks with patented formulations will continue to dominate the scene for a number of years before generic formulations will be cheaply available as we see for conventional inkjet printing.

Spray on Solar PV

New Energy Technologies Inc. have been promoting a new spray-on, see through solar PV coating which can be applied to glass windows.  Earlier this year they were indicating that around 20 new patent filings have been submitted for their proprietary SolarWindow™ technology.  Last year I reported on one of the early patent filings and the article can be viewed here.  Dr Xiaomei Jiang has been leading this effort with New Energy Technologies under a Sponsored Research Agreement at the University of South Florida (USF).

Two more patent applications have emerged this month from Dr Jiang at USF and they continue to reveal further details of the spray on techniques and solar PV architecture.

US20130255757: ORGANIC PHOTOVOLTAIC ARRAY AND METHOD OF MANUFACTURE

Publication date: 03/10/2013

Inventor(s): JIANG XIAOMEI JANE [US]; LEWIS JASON ERIK [US]

Abstract

The fabrication and characterization of large scale inverted organic solar array fabricated using all-spray process is disclosed, consisting of four layers; ITO-Cs2CO3-(P3HT:PCBM)-modified PEDPT:PSS, on a substrate. With PEDPT:PSS as the anode, the encapsulated solar array shows more than 30% transmission in the visible to near IR range. Optimization by thermal annealing was performed based on single-cell or multiple-cell arrays. Solar illumination has been demonstrated to improve solar array efficiency up to 250% with device efficiency of 1.80% under AM1.5 irradiance. The performance enhancement under illumination occurs only with sprayed devices, indicating device enhancement under sunlight, which is beneficial for solar energy applications. The semi-transparent property of the solar module allows for applications on windows and windshields, indoor applications, and soft fabric substances such as tents, military back-packs or combat uniforms, providing a highly portable renewable power supply for deployed military forces.

US20130263916: ALL SPRAY SEE-THROUGH ORGANIC SOLAR ARRAY WITH ENCAPSULATION

Publication date: 10/10/2013

Inventor(s): LEWIS JASON ERIC [US]; JIANG XIAOMEI JANE [US]

Abstract

An inverted organic solar photovoltaic cell is described that may be fabricated onto rigid or flexible substrates using spray-on technology to apply the various layers of the cell. Indium tin oxide with a thin layer of cesium carbonate functions as the cathode for the novel inverted cells. An active layer of poly-3(hexylthiophene) and [6,6]-phenyl C61-butyric acid methylester having a thickness around 200 nm to 600 nm facilitates a high level of light transmittal through the cell. A modified PEDOT:PSS, made by doping a conductive polymer with dimethylsulfoxide (DMSO), functions as the anode. A method of forming the inverted organic solar photovoltaic cell is also described using gas-propelled spraying to achieve thin layers. After the layers are formed, the cell is sealed using a vacuum and temperature-based annealing and encapsulation with UV-cure epoxy.

Phil’s Comments:

These applications are going through the patent office examination process so it is difficult to comment on the claims until we know what will actually be allowed.  The claims do make reference to spraying and the second application indicates that nitrogen is used as a propellant.

The device is an inverted solar cell design and may be fabricated onto both rigid and flexible substrates. Exemplary substrates include cloth, glass, and plastic. For example, the substrate may be a low alkaline earth boro-aluminosilicate glass.

Two figures from the second application are shown below:

FIG. 1 is a diagram that depicts the modified PEDOT:PSS as it is sprayed onto the substrate through a stainless steel shadow mask with an airbrush. Nitrogen is used as the carrier gas at a pressure of 20 psi.

FIG. 13 is a diagram showing the cross sectional view of the device architecture of an inverted solar array showing series connection

Figure 1 Capture2

Printed Electronics via Electrophotography

There are many different technologies used for printing electronic circuits such as screen printing, flexography, gravure, offset lithography and inkjet – a review of these can be found on the Wikipedia page for Printed Electronics.  One of the printing technologies which is not currently used is electrophotography although there have been various publications including patent applications that have proposed this route.

A recent patent alert I received indicated that Eastman Kodak has just been granted a method patent for producing a printed circuit using electrophotography.  The company is just emerging from chapter 11 bankruptcy and one of its stated aims is that it will focus on commercial printing.  This patent therefore fits well with its new strategy.  Although the patent title indicates a printed circuit board the description makes it clear that flexible devices are envisaged such as RFID, sensors and flexible displays.

The patent is US8497057 and was published on 30 July 2013.

Title: Method of Producing Electronic Circuit Boards using Electrophotography

Inventors: Thomas N Tombs; Donald S Rimal

Filed: 14 Sept 2012 and is a division of US 12/341099 filed on 22 Dec 2008

Abstract: The present invention provides a method producing printed electronic circuits using electrophotography.

The granted claims read as follows:

1. A method for producing a printed circuit, the method comprising performing the following steps in order:

charging a primary imaging member;
creating an electrostatic latent image by image-wise exposing the primary imaging member;
image-wise depositing thermoplastic particles onto the primary imaging member;
transferring the thermoplastic particles to an electrically insulating substrate;
a first fixing step of permanently fixing the transferred thermoplastic particles;
depositing conductive particles over the substrate;
a second fixing step of permanently fixing the conductive particles on the fixed thermoplastic particles so that conductive paths are formed between fixed conductive particles; and
removing conductive particles from portions of the substrate other than that coated with the fixed thermoplastic.

2. The method according to claim 1, wherein the conductive particles is permanently fixed by the application of heat.

3. The method according to claim 1, wherein the conductive particles is permanently fixed by the application of pressure.

4. The method according to claim 1, wherein the conductive particles is permanently fixed by the exposure to solvent vapor.

5. The method according to claim 1, wherein the conductive particles is metal.

 

Phil’s Comments

This method patent will shortly be complemented with the original patent which has been granted and is due to be published later this month (info obtained from the USPTO PAIR database).  I will post the details of this one when it is public.  I was interested to see if this was one of the first granted patents for electrophotography and had a quick look through the citations and examiner’s search results.  The USPTO PAIR database is a mine of information when you want to investigate the process by which a US patent is granted and see the comments made by the examiners.

Although a number of documents were found in the search none was considered relevant enough to impact the inventive step of the above claims as they are finally worded.  It should be noted that considerable changes were required to the original 2008 application.

I did a brief search for the keywords electrophotography and printed electronics in titles and abstracts came up with the following:

US7638252: Electrophotographic printing of electronic devices

and

US20070234918 A1:  System and method for making printed electronic circuits using electrophotography

This patent application was never granted and was abandoned.

From the references and citations it is clear that electrophotographic approaches for printed electronics have been documented well before 2008.  However, the Eastman Kodak patent has described a stepwise process which is somewhat different to the prior art and reviewing the prosecution it is clear that considerable detail has been gone over in agreeing the allowed claims over the prior art.

 

 

 

Copper Inks for Printed Electronics

I recently spotted a patent for copper based metallic inks jointly granted to Applied Nanotech Holdings, Inc. and Ishihara Chemical Co., Ltd.  The conductive inks I have previously reported on have been silver or graphene based, these can be very expensive and so there is always interest in a lower cost alternative.  Copper metal is a standard in the electronics industry and is about one tenth the cost of silver.

Patent summary:

US8404160   –  METALLIC INK

Inventor(s): LI YUNJUN [US]; ROUNDHILL DAVID MAX [US]; LI XUEPING [US]; LAXTON PETER B [US]; ARIMURA HIDETOSHI [US]; YANIV ZVI [US]

Applicant(s): APPLIED NANOTECH HOLDINGS INC [US]; ISHIHARA CHEMICAL CO LTD [JP]

Filing date: 31/03/2009
Issue date: 26/03/2013

Abstract
A metallic ink including a vehicle, a multiplicity of copper nanoparticles, and an alcohol. The conductive metallic ink may be deposited on a substrate by methods including inkjet printing and draw-down printing. The ink may be pre-cured and cured to form a conductor on the substrate.

Claim 1:

1. A conductive metal ink comprising: a vehicle comprising two or more oxygenated organic compounds; copper nanoparticles; and a medium length chain aliphatic alcohol, wherein the ink does not comprise a binder.

There are a further 23 claims giving more details of the components mentioned in claim 1.

Two figures from the patent give a flow chart for two processes which can be used:

Direct printing:

ink1

Patterning after the ink deposition:

ink2

Phil’s Comments

This is a key patent for copper inks and has a broad first claim which had to be modified from the original application by the addition of the restriction that the ink does not contain a binder and I suspect this was to get around some of the prior art identified by the patent examiner.

Six very detailed examples are given which illustrate the invention and provide further details of the printing process, the curing or sintering that is applied to produce the conductive tracks on a range of materials including flexible substrates.