Nanotechnology Blog

There are starting to be some interesting proposal being developed that use properties of nanomaterials.  This blog will cover three recent published reports relating to 1) food; 2) non-toxic graphene; and, 3) graphene for cooling electronics.

Food: In a paper in Journal of Agricultural and Food Chemistry, Researchers from Washington University (St. Louis, Missouri) [Ref. 1] present findings on a means of improving crop production by using nanomaterials.  An article by UPI [Ref. 2] puts the finding in more general terms.  As the requirement for additional food production increases, farmers employ more fertilizers.  One of the key components in phosphorous.  There are potential problems with this. When the excess fertilizer is washed from the field, it enters the waterways.  As it concentrates, it aids the growth of oxygen depleting algae, which kill fish.  There was also a comment that if farmers continue to use the phosphorous containing fertilizers at the current rate, there is the potential of running out of readily available phosphorous. The consequences are reduction in food supply, increase in the cost of food, and an increase in hunger.  Even if it were 100 years instead of the projected 80 years, the decrease in the availability of phosphorous will have an impact on society.

The researchers created zinc oxide nanoparticles the aids plant roots increase their ability to absorb the phosphorous in the soil.  The zinc interacts with three plant enzymes and enables the enzymes to convert the phosphorous into a less complex version that is easier for the plant to absorb.  The zinc oxide is applied to the plant leaf; it enables the plant to absorb 11% more phosphorous from the soil.  The ability to more effectively use the existing phosphorous means that less will be required to increase the plan harvesting.  (This is assuming that the mechanism will work similarly with all plants, which needs to be prove.)  The interesting thing about this work is that the zinc oxide is produced by a fungus.  This means that there is not a need for a complex manufacturing process to produce the nanomaterial.

Non-toxic: An interesting announcement was released on April 16, 2016 by Directa Plus. [Ref. 3]    In the announcement, the company stated that “all of its graphene-based products have received international certification from Farcoderm Srl (a toxicity testing agency) confirming them to be safe for human contact.  The material is manufactured in Lomazzo, Italy.  The company supplies material that in incorporated into sportswear and other products.

Graphene for cooling: Researchers in Gothenburg, Sweden announced the application of functionalized graphene nanoflakes-based film. [Ref. 4] The key to the process is the addition of molecules added to the surface of the material “to encourage various chemical and physical properties.”  They are incorporating amino-silane molecules to improve the in-plane heat conduction.  There results were published in the Journal of Nature Communications, where the full article is available. [Ref. 5] They measured significantly lower temperatures at previously identified hotspots on electronic devices.  For those interested, the article contains a significant amount of detail on their understanding of the processes involved.

The impact of being able to remove heat from the circuit itself enables the more effective operation of the electronics, which should result in a longer life.  However, there is a very large “if”.  For this heat transfer to be effective, the heat that is transferred must be removed from the entire electronics assembly.  Unless this removal occurs, the heat will remain in the entire package and result in a heat buildup.  Dissipating heat from a large package is continually being worked and is an easier problem to solve than the one this concept addresses.

References:

1. http://pubs.acs.org/doi/abs/10.1021/acs.jafc.5b05224
2. http://www.upi.com/Science_News/2016/04/29/Nanoparticles-offer-a-boost-to-food-crop-production/9711461946901/?spt=rln&or=3
3. http://www.directa-plus.com/Press/Directa%20Plus%20receives%20safety%20certifications%2021.04.16.pdf alternate access through http://www.directa-plus.com/
4. http://www.upi.com/Science_News/2016/04/29/New-graphene-based-film-may-keep-your-next-laptop-cool/9781461937124/?spt=rln&or=5
5. http://www.nature.com/ncomms/2016/160429/ncomms11281/full/ncomms11281.html

Currently, I am involved in writing a chapter on information reliability for a nano-safety book that should be published by early 2017.  My colleague, Evelyn Hirt, who has been leading this chapter effort, found some interesting developments in reviewing the traditional sources of nanotechnology information.  The typically recognized governmental sites are still functioning.  A number of new sites, which have connections to various government agencies around the world, have been added.  There are still a number of sites that are maintained through government funding.  Traditionally, these sites contain the latest information.  Some sites are either disappearing or have become stagnant, probably due to lack of funding.

Non-governmental organizations have, like the Royal Society of Chemistry and The American Chemical Society, have information available to both their members and the general public (although some information requires paying a fee).  These organization apply a portion of their members’ dues to creating and maintaining a database that can be very useful.

Do not expect to find most of the information that will probably need.  As of 2011 there is information on the Chemical Abstract Service for under 63 million (63 x 10⁸) chemical sequences.  Considering the known elements, the estimates are that over 10²⁰⁰ possible individual nanoscale particles.

Information on the web is another story.  The Internet, which was originally the ARPANet (1968 RFQ), was designed for the rapid communication of scientific data.  Peer review is typically a long process with peer reviews, comments to the authors, rebuttals, decision on publication value.  Rapid dissemination of information at that time was by air mail instead of surface mail.  There was a need to more rapidly share scientific information.  Consequently, the ARPANet was conceived to solve this problem among universities and scientific organizations.  This has evolved into today Internet with high speed communications. Today there are billions of different sites with a vast array of “information.”

While all the types of sources mentioned above normally provide good information, the information on the web is not always accurate.  The explosion of data available on the web is not always beneficial.  Information needs to be checked and verified.  There are other sites that previously had been key sources of information, and now are no longer maintained due to funding issues.  Consequently, the data provided is aged and may not be the latest available information.

Even with governmental site, there may be issues.  Occasionally, there have been conflicting announcements from different approaches issued by different agencies within one government department.  In 2008, two of the US Environmental Protection Agency programs, Office of Pesticide Programs and the Office of Pollution Preventions and Toxics, issued conflicting directives on what would be considered a new chemical based on size alone and the other indicating that this would not be the case if the material was used previously.

With the openness of the internet, anyone can post anything, accurate or not.  There is no overseeing guidance.  In addition, there is a greater degree of polarization of opinions and the lack of discourse on scientific findings.  While there always have been differences of opinion, today’s approach appears to be to attack the opposing side.  Even politics seems to be getting into the determination of scientific fact.    Senator Whitehouse (Dem, RI) is threatening to use RICO (Racketeer Influences and Corrupt Organizations Act) to silence researchers with opinions that differ from his supporters [Ref. 1].  Twenty scientists have asked the President to use the RICO to silence critics of their stance [Ref. 2].  This direction is ominous and can severely inhibit scientific research.

Consequently, the ability to obtain accurate, factual information is becoming more challenging.  This requires the individual to do more investigation to find out the truth.  One needs to check and double check.  All I can say is “Good Hunting.”

References:

1. http://www.weeklystandard.com/senator-use-rico-laws-to-prosecute-global-warming-skeptics/article/963007
2. http://dailycaller.com/2015/09/17/scientists-ask-obama-to-prosecute-global-warming-skeptics/

Challenges are not uncommon in developing new technologies. The current topics that are most in the publications are medical nanotechnology and the so-called two dimensional materials. Electronics constructed using the 2-D materials is being experimented with, but there have not been published results of significant advancements. Fuel cells with 2-D materials appears to currently be a topic of strong interest with most of the focus on graphene. The term 2-D materials is employed as being more inclusive of the current research, which is evaluating other materials with superior properties. A critical objective of the development of 2-D materials is creating a low cost process for producing large quantities of defect free material.

Medical: The Center for Responsible Nanotechnology [Ref. 1] has a long list of potential medical applications that when/if developed can be of significant benefit. If you want to do a comparison of where development is today, AZO nano [Ref. 2] has a 2005 reference article on “current” concepts. An issue with developments in the medical field is that the process for developing a product that can be used in humans requires a regulatory process that can significantly exceed seven years. In certain cases, the EU has streamlined processes. There are some cancer drugs that are available in the EU. Consequently, people need to explore treatments available around the world.

Graphene Electronics: The topic of graphene has been covered in a number of blogs. As has been discussed, the major issue is the manufacture of inexpensive, defect free material. There are efforts to create electronic systems that operate in realms that are unachievable without nanotechnology. There is a report from the Max Planck Institute [Ref. 3] on the potential for terahertz operation due to picosecond electrical conduction. There is a presentation from C. Y. Sung of IBM [Ref. 4] on the development of graphene nanoelectronics. Recent development sin “ribbons” of graphene [Ref. 5] discusses a new approach to creating graphene for transistors. The fundamental problem is that the current methods of creating transistors (semiconductor circuits) is that they are manufactured at a rate of billions per minute. Anything that will be employed to surpass the existing circuitry must have the high volume manufacturing capability that exists in semiconductors today. That capability has not been proven yet.

Fuel Cells: Researchers are developing means of adding impurities into 2-D structures that can provide additional storage capability benefits [Ref. 6]. An overview of nanotechnology in Fuel Cells [Ref. 7] provides an overview of the fuel cell technology improvements. Graphene may be a replacement for platinum. Graphene and cobalt are another possibility. A web search will turn up many possibilities for additional materials. The issue for application still comes down to being able to manufacture the nanomaterials is sufficient quantities at a reasonable cost.

The long term view is that there is still much development that needs to be accomplished before we are able to reap the benefits of nanomaterials.

References:

1. http://www.crnano.org/medical.htm
2. http://www.azonano.com/article.aspx?ArticleID=1242
3. http://phys.org/news/2015-07-terahertz-barrier-graphene-nanoelectronics.html
4. http://www.nist.gov/pml/div683/conference/upload/Sung.pdf
5. http://www.technologyreview.com/news/540231/how-tiny-ribbons-of-graphene-could-power-a-faster-transistor/
6. http://spectrum.ieee.org/nanoclast/semiconductors/materials/hydrogen-treatment-of-graphene-makes-for-super-liion-batteries
7. http://www.understandingnano.com/fuel-cells.html

One of the benefits of the interest in nanomaterials and graphene in particular is that the tools for investigating the material properties and the means for producing the materials continue to evolve. Electronics and more specifically semiconductors have been challenged to operate at “high” temperatures. 125^oC is the “normal” maximum operating temperature for widely distributed electronics. This limit is the typical specified upper value for both military and automotive electronics. [Note: the temperature of a vehicle can reach these extremes in the engine compartment.]   This temperature limit was developed based on the stresses created in a device due to expansion/contraction, changes in the mobility of electronics at higher temperatures, possible unwanted chemical reactions (e.g., dendrite growth), and having minor lattice faults propagate. There are a number of other concerns, but these provide examples of issues with higher temperatures.

There has been s quantity of research in finding 2 dimensional materials that can be fabricated and exist in the presence of possible external factors. (For readers who are unfamiliar with 2 dimension materials, the term refers to crystalline materials that are one atom thick. Although, there are some unusual properties in materials that are a few atoms think and these may be included in the overall category.) Some of the early research investigated Boron Nitride (BN) and Molybdenum Disulfide (MoS₂). (A listing of some recent materials is available on Wikipedia [Ref. 1]. The potential applications have not matured. Research continues to look for materials that can provide reliable performance in extreme conditions.

Recent development [Ref. 2] have provided a hope for very high temperature electronics. MoS₂ has been shown to have the potential for transistors working above 220^oC. The explanation for MoS₂ being superior to Silicon is that the MoS₂ bandgap is 1.9 eV versus Silicon 1.2 eV. (Note: the actual material survives about the working temperature, but the entire circuitry has to be able to function.) When a semiconductor device is operated, there are portions of the device that are operating well above the measured temperature. A significant portion of the power into the device is converted into heat.

This brings us to the question: “So What?” The reason for the interest in higher temperature electronics is there are many applications where having better understanding of the actual events that are occurring would be very valuable. Applications where this would provide information includes jet engines and deep wells that include both oil & gas and geothermal. If you want to learn about higher temperature transistors, please check the work from the University of Utah on plasma transistors [Ref. 3] for potential applications in nuclear reactors at temperatures of up to 790^oC.

As pointed out in the last blog, the main issue will remain the ability to mass produce these novel devices in sufficient quantities. To compete against traditional transistors in most applications, the quantity produced must be very large. Current semiconductor manufacturing techniques produce billions of transistor per second with very high yield. We are not close to that with anything under development. It will be a while before that happens, but not an extremely long time.

References:

1. https://en.wikipedia.org/wiki/2D_materials
2. http://spectrum.ieee.org/tech-talk/semiconductors/devices/molybdenum-disulfide-shows-promise-for-hightemperature-electronics
3. http://spectrum.ieee.org/tech-talk/semiconductors/devices/a-transistor-for-blistering-nuclear-reactor-temperatures