EC Sets Limits on BPA in Toys

BPA in plastic toys.

The European Commission announced it is placing restrictions on the use of bisphenol A, or BPA, in toys designed for use by children under the age of 3.

The new limit — based on current levels outlined in European Standard EN 71-9:2005+A1:2007 — is “a strict limit” of a 0.1 mg/l migration limit in toys meant for children up to age 3, and for any toys designed for children to place in their mouths.

The limits are already being voluntarily used by the European toy industry. The European Commission says this has helped keep toy-based BPA exposure low when compared to exposure from contact with nonfood items such as cosmetics or dust. This is, notes the government, far lower than the exposure from BPA in the diet, based on information compiled by the European Food Safety Agency (EFSA).

Widely Used Compound

Bisphenol A — commonly referred to as BPA — is a synthetic compound with many uses, including in the production of polycarbonate plastic for electronics, automobiles, CDs and DVDs, and adult food and drink packaging. The addition of BPA to plastic makes it more flexible and shatterproof.

It is also frequently used in container linings; however, this use is under increased scrutiny. It was, for example, once used in the plastic in infant formula packaging in the United States. The plastic acted as a barrier between the formula and the metal or other materials in the container. Infant formula makers stopped using it when questions first arose about its role in fetal health. The United States Food and Drug Administration (FDA) later moved to ban the use of BPA in infant formula packaging based wholly on the fact that it is no longer used, and not because it is unsafe.

Endocrine Disruptors?

Some studies have reportedly found a link between exposure to BPA and disruption in the human hormone system. The risks these so-called endocrine disruptors pose to human health is a contentious issue among scientists, who have been embroiled in controversy and debate about BPA and other such chemicals.

Consumer and environmental groups have raised concerns about the chemical’s suitability in any food or beverage containers. Concern also has been raised about its use as a coating for cash register receipt paper. Some of these fears are irrational, some scientists have said.

Yet, in a conversation with The New York Times‘s Nicholas D. Kristof, John Peterson Myers, chief scientist at Environmental Health Sciences and a co-author of a study on BPA, said his family had stopped buying canned food and was taking other precautions to limit its BPA exposure:

We don’t microwave in plastic. [...] We don’t use pesticides in our house. I refuse receipts whenever I can. My default request at the ATM, known to my bank, is ‘no receipt.’ I never ask for a receipt from a gas station.

Voluntary End of Use

Most of the bans to date have occurred after manufacturers voluntarily stopped using the substance. This was the case in the U.S., where, although it had not been used for years in baby bottles and sippy cups, the federal government instituted a ban on its use in those items.

The European Commission summarized:

The complex health effects of BPA, including endocrine disrupting effects, are still under scientific evaluation at the EFSA and in other scientific fora. If relevant new scientific information becomes available through the ongoing scientific work, the limit that the Commission has now adopted would have to be reviewed.

Image by Dulcenombre Maria Rubia Ramirez/123RF.
Source: “EU Sets Strict Limit for Content of BPA in Toys Owing to Health Concerns of Children,” SpecialChem, June 27, 2014.
Source: “Bisphenol A (BPA) Strictly Limited in Toys,” European Commission press release, June 25, 2014.
Source: “Public Consultation on the Draft Opinion on Bisphenol A (BPA) — Exposure Assessment,” European Food Safety Authority, September 15, 2013.
Source: “Tests Find Chemical-Laden Receipts at National Retailers,” Environmental Working Group, July 27, 2010.
Source: “Debate Builds over Regulation of Bisphenol A and Other Endocrine Disruptors,” Scientific American, September 20, 2013.
Source: “How Chemicals Affect Us,” by Nicholas D. Kristof, The New York Times, May 2, 2012.

Polymer Opals: Colorful, Lasting Material

The flexible polymer opal changes color when compressed.

A new material inspired by the structure of natural gemstones has many properties its earthy counterparts do not.

Opals, which are among the most vividly colored materials in nature, obtain their colors from the reflection of light. Based on this property, the polymer opal, created by researchers from the Fraunhofer Institute for Structural Durability and System Reliability and University of Cambridge, is a flexible, colorful material that will not fade over time and that changes color when stretched.

Natural Opals

Opals form in nature when water evaporates, leaving behind tiny silica spheres. These deposits are suspended in the earth and are ordered so that the spheres diffract the visible light, which cause the beautiful, intense colors in the gems. In polymer opals, silica is replaced by nanoparticles with a rubbery outer shell.

The researchers explain:

Gemstone opals achieve their structure by the regular stacking of perfectly round glass spheres. Polymer opals also consist of ordered spheres. Using clever chemistry similar to that used in the production of latex paints, a mass of nearly identical spheres for polymer opals are synthesised with a hard central core of crosslinked polystyrene, bonded to a soft outer shell of polyethylene acrylate that has the consistency of chewing gum.

Synthetic Opals

Although synthetic opals were first made in the 1970s, they are typically brittle and, add the researchers, aren’t suited for mass market applications.

To make these new synthetic opals, the researchers expose the spheres to high temperatures, which causes them to self-assemble into a 3D crystal with structural color. Structural color refers to a color in both nature and synthetics created by diffraction. This includes peacock feathers, butterfly wings, or photonic crystals.

At these temperatures, the soft outer shells deform while the central core material becomes ordered. This regular pattern diffracts lights. In other words: the internal structure produces the color; the outer shell provides it with its elastic properties.

The precise color of the polymer opal is based on the nanoparticle size. There are small (171 nm), medium (191 nm), and large (266 nm) particles that produce blue, green, and red opals.

Changing Colors

Polymer opals can temporarily change color by deforming — that is, stretching or twisting — the material. Such deformation causes the color to change based on the space between particles changing. This change alters the wavelength at which the material reflects light. Stretching, for example, causes a green sample opal to become blue when stretched; a blue sample becomes green when compressed. These color shifts can be temporary. This property could be ideal for use in strain sensors. Such color changes should be able to show the level of stress an item attached to the material is undergoing.

Possible Applications

The colorfast nature of this material would be attractive in fabrics, as the polymer opal material could replace toxic dyes. Additionally, the color wouldn’t fade or run.

Another possible application: an alternative to holograms used in paper currency to prevent counterfeiting. The color-changing properties are difficult, but inexpensive to reproduce.

The researchers add:

A real advance is that we can make these photonic crystals by standard plastic manufacturing techniques. They are flexible, making them some of the most durable opalescent materials available, and they are suited for mass production and incorporation into consumer items.

The researchers are working to commercialize the material; however, the polymer opals are already being used in creative ways. London-based designer Rainbow Winters included fabrics based on the material at a fashion show in Paris. They also have applications in both security and sensing applications.

Among the future research they are exploring includes producing a single sheet in which there are different colors on different areas of the sheet rather than a single, uniform color.

Jeremy Baumberg, professor of nanophotonics in the University of Cambridge, department of physics, concludes:

The crucial thing is that by assembling things in the right way you get the function you want. [...]  It’s such a good example of nanotechnology — we take a transparent material, we cut it up in the right form, we stack it in the right way and we get completely new function.

Image courtesy University of Cambridge.
Video: dres2video2share, YouTube.com.
Source: “Nanosphere-Laced Polymer, Polymer Opals That Change Color Under Stress,” Plastemart.com.
Source: “Polymer Opals,” University of Cambridge, Colours.
Source: “Nanomaterials Up Close: Synthetic Opal,” by Harry Beeson, University of Cambridge, Research, June 13, 2014.
Source: “Trapping the Light Fantastic,” by Gen Kamita and Jeremy Baumberg, University of Cambridge, Research, June 16, 2014.

Polymer-Based Springs Added to Autos

Lightweight, composite car springs.

A composite spring, left, next to a conventional metal spring.

A new polymer composite suspension spring promises to bring numerous benefits to the automotive industry, benefits that drivers should ultimately be able to appreciate as well.

Audi and Sogefi, an Italian automotive parts manufacturer, collaborated on the development of a glass fiber-reinforced polymer spring, designed to replace steel springs used as part of a car’s suspension.

The spring is light green in color and reportedly is beefier than its steel counterpart. It also is slightly larger in diameter and features fewer coils than a steel spring.

The springs are made using a process patented by Sogefi in which long glass fibers are twisted together. An epoxy resin is added before additional fibers are mechanically wrapped around the twisted glass core. These other fibers are placed in such a way as to counteract possible stresses. The structure is then then cured at temperatures exceeding 100°C.

“The GFRP springs can be precisely tuned to their respective task, and the material exhibits outstanding properties,” states Audi. The material “does not corrode, even after stone chipping, and is impervious to chemicals such as wheel cleaners.”

Polymers’ Roles in Auto Industry

Polymer composite materials have been used in the automotive industry for several decades. The 1953 Chevrolet Corvette was one of the first models to feature such materials. Typically, glass fiber-reinforced polymers have been used in the industry, but other types of polymer composites, including thermoplastic composites and carbon fiber-reinforced polymer composites, are promising, according to US Department of Energy researcher Sujit Das.

Today about 245 pounds of plastics and composites are used in a typical vehicles, or about 8 percent of an automobile. This is a relatively small increase from the mid-1970s, when about 170 pounds were used per vehicle. Smaller, more fuel-efficient vehicles generally contain more plastics relative to their total weight; however, minivans contain more composite parts by weight.

The use of glass-reinforced polymers in a vehicle’s structural components could result in a 20 to 35 percent reduction in the vehicle’s weight. The use of carbon fiber-reinforced polymer materials may reduce an automobile’s weight by 40 to 65 percent. The new springs are 40 percent lighter than the steel spring it is replacing.

A steel spring for an upper mid-size car weighs about 2.7 kilograms, while the new glass fiber-reinforced polymer spring with the same properties weighs about 1.6 kilograms. The four springs on the new Audi, therefore, promise to reduce its weight by about 4.4 kilograms.

Das further observes:

Important drivers of the growth of polymer composites have been the reduced weight and parts consolidation opportunities the material offers, as well as design flexibility, corrosion resistance, material anisotropy, and mechanical properties. Although these benefits are well recognized by the industry, polymer composite use has been dampened by high material costs, slow production rates, and to a lesser extent, concerns about recyclability.

Nonstructural Elements

Composites are most often used for nonstructural elements in niche-market vehicles with annual production volumes of less than 80,000. Some parts using composites include bumper systems, instrument panels, leaf springs, drive shafts, compressed natural gas fuel tanks, intake manifolds, and wheel covers.

Dr. Ulrich Hackenberg, member of the board of management for technical development at AUDI AG, states in a release, “The GFRP springs save weight at a crucial location in the chassis system. We are therefore making driving more precise and enhancing vibrational comfort.”

Although Audi claims the springs can be used to help them tune the suspension, ultimately giving “a more precise driving experience,” Motor Trend is waiting to evaluate the claims. “It remains to be seen how the polymer springs hold up over time, but we can see how the new springs perform when they arrive on a new model later this year.

Other benefits, according to Sogefi, are reduced emissions in the manufacturing process, and when driving, as well as lower fuel consumption.

Audi plans to use the glass fiber-reinforced polymer suspension springs in an undisclosed new upper-midsized model, which some observers speculate will be the A6 or A7, to be released in Fall 2014.

Image courtesy Audi Media Services.
Source: “Sogefi, Audi Develop New Suspension Spring Technology,” reporting by Agnieszka Flak, editing by Mark Potter, Reuters.com, July 3, 2014.
Source: “Audi Polymer Suspension Springs Arrive on Unnamed Model This Fall,” by Jason Udy, wotmotortrend.com, June 30, 2014.
Source: “Audi Set to Cut Vehicle Weight with Introduction of Fiberglass Springs,” by Scott Collie, Gizmag.com, July 2, 2014.
Source: “New Patented Lightweight Springs to Be Introduced by Audi by Year End,”sogefigroup.com, July 3, 2014.
Source: “Audi Bringing New Lightweight Springs to Production Models,” Audi.com, June 30, 2014.

Technique Grows Metal-Organic Membranes Inside Fibers

Growing metal-organic framework membranes inside hollow polymer fibers.

Georgia Tech researcher Andrew Brown places a finished hollow fiber metal-organic framework (MOF) membrane module into a testing apparatus to measure its gas separation properties.

A new fabrication method for growing metal-organic framework membranes inside hollow polymer fibers has been developed by Georgia Institute of Technology researchers, who say it promises to change large-scale, energy-intensive chemical separation processes.

This is thought to be the first method for growing metal-organic framework membranes in hollow fibers.

Molecular sieving membranes use semipermeable materials to separate molecules from mixtures made via chemical reactions, or from raw material feedstocks. The membranes pass only certain molecules through their pores. To date, other researchers have developed membranes using crystalline materials known as zeolites, but these are costly and not widely available, which has hampered their wider use.

Affordable Technology

Researchers thought metal-organic framework membranes had the potential to replace other energy-intensive industrial separation processes, but first, they had to find a method for making them affordably and in large volumes.

They used hollow fibers spun from inexpensive polymers to create the new membranes. Each fiber is a few hundred microns in diameter. A microfluidic technique brings together reactants needed to form the membranes inside the fibers. Since the inner diameter of the fibers may be 100 microns or less, the amount of reactant that can be used to fabricate the membrane is limited; the size also affects the physical and chemical forces responsible for membrane formation.

To control the location of the membrane films, researchers had to change the flow and the position of both the reactants and solvents used in the process, using, for example, two different solvents flowing in opposite directions to deposit the material selectively within the hollow fibers. In some cases, the films were formed outside or within the fiber structures. This allowed the process to be scaled up, thereby lowering the cost.

Scaling up Production

Fabricating hollow-fiber metal-organic framework (MOF) membranes.

This close-up photograph shows the prototype reactor module used to fabricate hollow-fiber metal-organic framework (MOF) membranes at Georgia Tech using the interfacial microfluidic technique.

After they were able to make a membrane with a single hollow fiber, the team sought to make membranes in parallel using multiple hollow fibers preassembled into a module. Specifically, they used a compound known as ZIF-8 — zeolitic imidazolate frameworks, a metal organic framework with properties like zeolites, including porosity — to make the metal-organic framework inside three fibers at the same time.

Based on their findings, the researchers say they may be able to preassemble large bundles of the polymer fibers, then coat these at the same time with some sort of metal-organic framework to make larger metal-organic framework membranes with a greater surface area. A 1-cubic-meter hollow-fiber membrane module could contain 10,000 square meters of membrane area.

Gas and Liquid Separation

The use of such metal-organic framework membranes may eventually be able to reduce the costs of other more energy-intensive processes for gas and liquid separation, such as distillation. It could also decrease the amount of carbon dioxide generated in the process.

Demonstrations of these novel membranes have been limited to separating hydrocarbon gas mixtures — hydrogen from hydrocarbon mixtures and propylene from propane — that might be used by the petrochemical industry; however, this membrane processing technique could have broader applications, according to Christopher Jones, a Georgia Institute of Technology professor of chemical and biomolecular engineering who worked on the project:

The approach we have developed could open the door to a whole new class of molecular sieving, polycrystalline film membranes. [...]  Such membranes could revolutionize how oil and chemical companies carry out gas and liquid separations, for example, by replacing energy-intensive and expensive cryogenic distillation processes with more energy-friendly membrane separations.

It could be used for other industrial processes, including the production of bio-based fuels and chemicals.

Next, the researchers want to better understand the microscopic level conditions in the process. Understanding the chemical reactions and molecular-level transport processes that occur as the membrane is formed may help them optimize and scale their technique.

Additional collaborators included scientists formerly with Georgia Institute of Technology, now affiliated with The Ohio State University and SABIC.

The research was supported by Phillips 66 Company.

Images by Rob Felt, courtesy of the Georgia Institute of Technology by Rob Felt.
Source: “Interfacial Microfluidic Processing of Metal-Organic Framework Hollow Fiber Membranes,” by A.J. Brown, N.A. Brunelli, K. Eum, F. Rashidi, J.R. Johnson, W.J. Koros, C.W. Jones, and S. Nair,Science,Vol. 345 No. 6192 pp. 72-75, July 4, 2014; DOI: 10.1126/science.1251181.
Source: “Hollow-Fiber Membranes Could Cut Separation Costs, Energy Use,” PhysOrg, July 3, 2014.
Source: “Exceptional Chemical and Thermal Stability of Zeolitic Imidazolate Frameworks,” by K.S. Park, Z. Ni, A.P. Cote, J.Y. Choi, R. Huang, F.J. Uribe-Romo, H.K. Chae, M. O’Keeffe, and O.M. Yaghi, Proceedings of the National Academy of Sciences of the U.S.A., doi: 10.1073/pnas.0602439103, May 22, 2006.

John Recalls Pirates in the Lab …

Let us introduce you to …

John Winebarger

ACS Laboratory Technician and Quality Specialist

John Winebarger

John Winebarger, ACS laboratory technician and quality specialist

How long have you worked at PSI and what did you do before?

I’ve been at PSI for two years. Prior to that, I was in school at Virginia Tech getting a double degree in Biochemistry and Chemistry. I worked at the Fralin Life Science Institute at Virginia Tech in their biotechnology outreach program, which loaned out all-inclusive science kits to Virginia high schools. They included gel electrophoresis, column chromatography, and immunology.

Do you think anything you do during a typical day would surprise people?

Usually after arriving I’ll head up to the front kitchen and brew a cup of Yorkshire tea and chat with the other caffeine addicts for a few minutes. Then I’ll touch base with my lab manager Alan and plan out my day based on the work he assigned me. Then I get to work. I have a few other random responsibilities as well, such as overseeing the glassware stream for the company, ensuring that all the labs have adequate glassware for their needs and ensuring that dirty stuff is addressed promptly by our general technicians. I’m also loosely affiliated with the Quality Department, evaluating our vendors and maintaining their documentation in our quality system.

What’s a common misconception about the work you do, and why do you think that is?

Probably the biggest misconception is that the work we do always gives us concrete results, unwaveringly, and quickly, much like how you see it happen on television. In reality, the results aren’t always so absolute, and they’re almost never quick and convenient. A lot of the science we do requires a skilled pair of eyes to look through the data and make a proper interpretation, or sometimes, no interpretation if the experiment simply didn’t work.

Behind the scenes, for the more complicated projects with larger scope, there sometimes has to be some trial and error before you find the best way to tackle the questions the client wants answered. Often this is hashed out in advance by our experts, but sometimes you don’t find out what will work until you’re actually in the lab trying it. Sometimes this can mean treading new ground internally for our clients and expanding our scope of expertise.

What’s been your favorite project at PSI so far, and why?

It’s hard to pick any one project, but it’s always the most fun to test the more random things we receive. You never know what new, challenging, and interesting surprise is walking in with the mail any particular day. For example, one week we might test tear gas, and the next, analyze seal blubber.

For the record, the smell of rancid seal blubber is not pleasant.

Another one that comes to mind isn’t really appropriate to talk about, but I’ll say we analyzed manufacturing problems in an adult product and leave it at that. Those kinds of projects are where a lot of the adventure of this job comes in.

What’s the weirdest thing you’ve ever done at PSI?

I’d have to say doing lab work dressed as a pirate is up there. Our annual Talk Like a Pirate Day celebration creates an odd day at a testing lab, with people alternating between lab work, sword fights in the parking lot, and 17th century pirate murder mysteries in the conference room. Just remember that an eyepatch isn’t appropriate lab PPE.

PSI is a unique place, no doubt about that.

PSI prides itself of accepting new challenges. What project(s) have challenged you and given you satisfaction upon completion?

I can’t get into specifics of course, due to client confidentiality, but I did a lot of work for a particular patent litigation case where we analyzed a set of knock-off medical devices manufactured in China and compared them to the patented domestic product. That case stands out because I remember getting to follow it until its resolution in the courts, which was particularly satisfying.

If someone made a TV show or film about PSI, who would you want to play you, and why?

Chris Hemsworth, so one day I can sit down with my kids and watch it and say, “Look how handsome your dad was when he was young! And also he was a superhero for a while, no big deal.”

Thinking back on great scientists in history … who is your favorite and why?

There are too many instrumental figures in the past to just choose one, so I’m going to aim for the present instead. I think Neil DeGrasse Tyson is one of the most important scientists of the day. Not for his discoveries or research, but for his ability to convey science to the non-scientific masses. There’s a troubling anti-science sentiment that exists in some circles in the country these days, so it’s hard to overestimate the importance of a scientist who can connect with the average American so well, and turn science into something more than an annoying class from high school. Without scientists like him, the value of science – not to mention the understanding of its basic tenets — would be lost on so many people.

What do you do for fun outside of work? Does it relate to what you do during the week?

At the moment, my interests include traveling internationally whenever possible, taking good care of my dog, running, and exploring/camping in the great outdoors. So it really has nothing to do with my job, except that I get to thank PSI for cultivating my interest in running. In the past year, a good group of us have started training for 5Ks (and eventually 10Ks). I guess that rubbed off from the Rancourts, a family full of runners.

3D Printing Creates Artificial Blood Vessels

Scientist have developed a promising technique for the vascularization of 3D-printed organs.

Blood vessels form an intricate network, transporting nutrients and oxygen throughout the body and disposing of waste, keeping organs working properly.



Using 3D printing, medical researchers have been able to create artificial blood vessels based on the human circulatory system.

According to the international team of researchers from the University of Sydney, Harvard and Stanford universities, and the Massachusetts Institute of Technology, the technique is fundamental for growing large, complex tissues, and is a step toward printing transplantable tissues and organs.

Intricate Network

Blood vessels form an intricate network, transporting nutrients and oxygen throughout the body and disposing of waste, keeping organs working properly. Cells die without an adequate supply of oxygenated blood. The intricacy involved in growing blood vessels and capillaries has typically posed a challenge for medical researchers trying to move toward the engineering of large tissues and organs.

Ali Khademhosseini, a biomedical engineer and director of the Brigham and Women’s Hospital Biomaterials Innovation Research Center, explains:

Engineers have made incredible strides in making complex artificial tissues such as those of the heart, liver and lungs. [...] However, creating artificial blood vessels remains a critical challenge in tissue engineering. We’ve attempted to address this challenge by offering a unique strategy for vascularization of hydrogel constructs that combine advances in 3-D bioprinting technology and biomaterials.

Template for Vessels

Their technique for constructing the network of blood vessels is based on 3D printing, which enabled them to make a template of numerous interconnected fibers. This fiber structure was used as a mold for the artificial blood vessels. The mold was created using agarose, a sugar-based molecule fiber and natural hydrogel-producing polymer.

The mold was covered with a protein-based material known as a hydrogel and reinforced with photocrosslinks, a means of forming bonds between molecules. Several common hydrogels were tested by the researchers, including methacrylated gelatin, a material often used in tissue engineering, and poly(ethylene glycol)-based hydrogels.

Tiny Channels

The agarose templates, when physically removed from the structure, leave a network of tiny channels. This material does not have to be dissolved, which has the potential to affect any cells encased in the gel. These channels are coated with human endothelial cells — the same cells that line human blood vessels — that have a range of functions, including creating new blood vessels.

These new bioprinted vascular networks, say the researchers, “promoted significantly better [endothelial] cell survival, differentiation and proliferation compared to cells that received no nutrient supply.” In other words, they work.

University of Sydney researcher Dr. Luiz Bertassoni explained the need this technology fills:

Thousands of people die each year due to a lack of organs for transplantation. [...] Many more are subjected to the surgical removal of tissues and organs due to cancer, or they’re involved in accidents with large fractures and injuries. While recreating little parts of tissues in the lab is something that we have already been able to do, the possibility of printing three-dimensional tissues with functional blood capillaries in the blink of an eye is a game changer.

Although tissues can be replicated in the lab now, what these researchers are ultimately striving to do is regenerate complex, functional organs through a marriage of engineering and medicine. Perhaps one day, they theorize, a patient would be able to walk into a hospital and have an organ printed according to their specific needs. This bioprinting technique could be used to properly print all the cells, proteins, and blood vessels needed from a prompt on a computer screen.

They consider the printed structures they are now making to be prototypes that will evolve as the technique is improved and refined.

Khademhosseini added:

In the future, 3D printing technology may be used to develop transplantable tissues customized to each patient’s needs or be used outside the body to develop drugs that are safe and effective.

The researchers published their work — “Hydrogel Bioprinted Microchannel Networks for Vascularization of Tissue Engineering Constructs” — in the online journal Lab on a Chip.

Image by blueringmedia/123RF.
Source: “Hydrogel Bioprinted Microchannel Networks for Vascularization of Tissue Engineering Constructs,” by L.E. Bertassoni, A. Khademhosseini, et al., Lab on a Chip, Issue 13, 2014, DOI: 10.1039/C4LC00030G.
Source: “3-D Printing Breakthrough: Researcher Calls Ability to Bioprint Blood Vessels a ‘Game Changer,’ ” by Punditty, AllVoices, July 1, 2014.
Source: Brigham and Women’s Hospital.
Source: “A Step Closer to Bio-Printing Transplantable Tissues and Organs,” University of Sydney, July 2, 2014.
Video: “3D Printing at BWH,” by BWH Public Affairs.

Novel Optical Gas Sensors Created With Polymers

MIT researchers have created a suspended polymer nanocavity that can detect small amounts of gases and other substances.

High-sensitivity detection of dilute gases is demonstrated by monitoring the resonance of a suspended polymer nanocavity. The inset shows the target gas molecules (darker) interacting with the polymer material (lighter). This interaction causes the nanocavity to swell, resulting in a shift of its resonance.


A new, compact sensor able to detect trace levels of gases has been made from microscopic polymer light resonators, materials that expand when specific gases are present.

These particular sensors are extremely sensitive and compact, and are able to detect very small numbers of molecules, according to researchers from the Massachusetts Institute of Technology Quantum Photonics Laboratory.

Precise Measurement

Central to the device is the material used in its photonic crystal cavity, polymethyl methacrylate (PMMA). This inexpensive and flexible polymer swells when it comes into contact with a target gas, changing the measurement of the cavity. The researchers infused the polymer with a fluorescent dye so it would change color in relation to the concentration of the gas, enabling extremely precise measurement.

Hannah Clevenson, a doctoral student in the electrical engineering and computer science department at MIT, who led the project’s experiments, explained:

These polymers are often used as coatings on other materials, so they’re abundant and safe to handle. Because of their deformation in response to biochemical substances, cavity sensors made entirely of this polymer lead to a sensor with faster response and much higher sensitivity.

They made the device with 400-nanometer-thin PMMA polymer films, patterned with structures between 8 and 10 micrometers in length by 600 nanometers wide. The films were then suspended in the air. The researchers experimented with embedding the films in tissue paper, which allowed 80 percent of the sensors to be suspended over the air gaps in the paper. Clevenson says surrounding the PMMA film with air enables the device to swell when exposed to the target gas. The optical properties of air allow the device to be designed to trap light traveling in the polymer film.

To test the device, they initially chose to detect isopropyl alcohol vapor. Two expected changes in the material occurred, that is, the swelling of the cavity and the change in the refractive index, however, the primary change in the polymer is swelling in reaction to the presence of gas.

Target Chemicals

The polymer material can be treated to interact specifically with various target chemicals, adding to the versatility of the MIT team’s sensor design. Still other gases could be detected, say the researchers, including low concentrations of ozone and acetone that corrode the polymer when present.

These photonic crystals allow state-of-the-art gas sensing on almost any rough or patterned surface imaginable, researchers say. The sensors are easily reusable since the polymer shrinks back to its original length once the targeted gas is removed.

The current detection sensitivity of these still-experimental devices is 10 parts per million. Gas concentrations as low as 600 parts per million can be measured. With additional refinement, part-per-billion concentration levels of various gases could be detected. The researchers are specifically interested in making additional improvements to the cavity’s fabrication. This may include adding a dopant to the material for brighter fluorescence or so it can be used with cavity transmission measurements.

The anticipated use for these devices is as sensors across industrial, environmental, and biological uses, including use in large chemical plants for industrial safety devices, or for detecting toxic gases in homeland security applications. In medical use, the polymer material could be treated for detecting specific antibodies.

Image by Hanna Clevenson/MIT.
Source: “High Sensitivity Gas Sensor Based on High-Q Suspended Polymer Photonic Crystal Nanocavity,” by H. Clevenson, P. Desjardins, X. Gan, and D. Englund, Applied Physics Letters, Volume 104, Issue 24 (DOI: 10.1063/1.4879735).
Source: “MIT Researchers Make Novel, High Sensitivity Optical Sensors That Swell When Exposed to a Target Gas,” EurekAlert.

Jenny Talks CSI, Bones, NCIS (and Reality)

Jenny Hazlett of PSI.

Jenny Hazlett, senior gas chromatography laboratory technician at PSI.

 

Today we’re chatting with …

Jenny Hazlett
Senior Gas Chromatography Laboratory Technician

How long have you worked at PSI and what did you do before?

Since September 2008. Before that I worked at Home Depot, UPS, and various temp jobs. 

Do you think anything you do on a typical day would surprise people? 

I generally start with a few cups of tea around 8 a.m. while I’m working on the schedule for the GC lab, getting updates from my lab partner about where we stand on various projects and what we want to accomplish for the day. By 9 a.m. we’re in the lab, prepping samples or analyzing data, maybe doing some instrument maintenance, maybe just cleaning up the lab if we’ve been too busy to keep up with it. Sometimes I take a mid-day break for lunch, sometimes I don’t — depends upon how much work there is to do. After lunch is more sample prep and/or data analysis, planning for the next day, and updating project managers about how their projects are going. I usually end up back at my desk around 5 p.m., updating my time sheet and making sure we’re ready for tomorrow.

What’s a common misconception about the work you do, and why do you think that is?

After watching shows like CSI, Bones, or NCIS, people believe that all you have to do to analyze samples is put them directly into an instrument and 5 minutes later read a printout that tells you exactly what it is, where it came from, and how much of it there is. There’s no instrument that is going to tell you that you have paint flakes from a car shop in the middle of Arizona, or that the liquid you found is water from a reservoir in upstate New York.

All that an instrument can do is give you data. That data will not be useful if the samples weren’t prepared properly. That process takes time. And running samples properly takes time. Much more than five minutes.

A GCMS can tell you that this sample has ions at 149 and 206. It takes a special skill set, along with knowledge of the sample itself and its intended use, to tell that what you are looking at is benzyl butyl phthalate. Maybe. Here’s a comic that explains it pretty well. I think it’s from xkcd, but I’m not certain. Comic from xkcd: A webcomic of romance, sarcasm, math, and language.

What’s been your favorite project at PSI so far, and why?

It’s weird, but I don’t think the good projects really stick with me. It’s like they just go in one ear and out the other. But the bad ones … those can give you nightmares five years after they went out the door. Maybe it’s because the good projects are generally the ones that go smoothly, that are easy and predictable. The bad projects are the ones that challenge you, make you pull your hair out for weeks, that constantly go wrong and force you to learn more and try harder every time.

I both love and dread the new projects that we’ve never done before (maybe no one has done them before), that will keep me up at night trying to figure them out, and that will make me scour scientific journals for ideas on how to proceed. I get a lot more satisfaction out of completing a project like that than I get from finishing up an easy project. And I learn more.

As a general rule, though, any time I get to drop plastic building blocks into liquid nitrogen, pull them out, then smash them with a 10 kilo weight, I’m a pretty happy girl.

What’s the weirdest thing you’ve ever done at PSI?

I don’t know that I can pick just one thing. Taking 3-foot-long bolt cutters to supposedly unbreakable plastic wine glasses? Shoving whole children’s toys into a huge grinder? Putting spit from various PSI employees through a filter? There’s almost always something weird to do (or going on) around here. It’s one of the things that keeps the job interesting.

PSI prides itself of accepting new challenges. What project(s) have challenged you and given you satisfaction upon completion?

There are so many of those. I just wrapped up a nasty bit of a project looking for glycols and 1,4-dioxane in various liquids. The client wanted it done according to an NIOSH method that involved small pumps pulling air through sampling tubes, but that wasn’t really applicable to this project. In the end I found a way to hook up needles to headspace vials, tubing, a nitrogen tank and the sample tube. It worked pretty well, and I hope that the client was happy with the result!

I also really enjoy the challenge of scheduling people, instruments, and projects when we’re really busy. I love having lots to do and making sure that everything happens when and where and how it should. Some of my favorite moments have been in the middle of huge validation studies (residual monomer) for biomedical clients, when I know that I’ve got three  weeks of work to do and I have to keep it going and organized. I love it when I’m done with one of those and everything is all neat and tidy and organized.

If someone made a TV show or film about PSI, who would you want to play you, and why?

I think that Jennifer Lawrence would be a decent pick. She’s much cuter than I am, but I’m OK with that. I think, though, that she has the confidence to appear dorky and slightly nuts, and highly uptight on the big screen. She’s smart, too, which can only help with the science part of my life. Plus she’s not afraid to be goofy, she’s so down to earth, and she’s got an … earthy … sense of humor like I do.

I’d feel so bad if they made Meryl Streep or Anne Hathaway play me. It would just be so mortifying for them. They’d do a great job. Meryl always does. She could probably find a way to make even my life look exciting and glamorous! So maybe I should root for Meryl?

Thinking back on great scientists in history … who is your favorite and why?

I don’t really have a favorite single scientist in history. I really admire the natural philosophers, though, who were sort of the first folks to try to explain the world in a nonreligious capacity. They looked — really looked — at the world around them and then used logic/philosophy to try to figure out what made it all tick. Aristotle, Anaximander, Plato, Heraclitus, Democritus … they made some amazing deductions about science without any of our modern instrumentation.

What do you do for fun outside of work? Does it relate to what you do during the week?

Pug rescue, flyball, lots of reading, snuggling with my dogs, hanging out with my best friend, cooking, running, playing video games. I’m getting ready to buy a house so I’m sure that there will be lots of home renovation in my future.

Turning Microscopy Into Art

Crystals of tartaric acid form a colorful pattern under polarized light.

Colorful crystals of tartaric acid, one of many compunds found in grapes and wine, in polarized light.

 

“Beauty in things exists in the mind which contemplates them.” — David Hume.

Scientists who use microscopy are often fascinated by the amazing beauty and complexity of the world on the micro scale. But since they are typically focusing on the data provided by these images, they forget the beauty. Turning microscopy into art is sometimes one step away. Here is how BevShots tell the story:

In 1992, a research scientist named Michael Davidson stumbled upon a genius idea right under his nose — literally. In his 25 year career through the many facets of microscopy, he had taken photographs under the microscope of a collection of items – DNA, biochemicals and vitamins. Looking for novel ways to fund his Florida State University lab, Davidson decided to take his microphotographs to businesses for possible commercial opportunities. While presenting his pictures to established retail companies, one necktie manufacturer changed his creative direction with just one word — cocktails. With this new direction, Davidson took his microphotography a step further [...]

Polarized microscopic images of cocktails, brews, and wines formed the Molecular ExpressionsTM Cocktail Collection of BevShots. The images are presented as art prints, neckties, scarves, and beach sarongs, and on glasses, coasters, and hip flasks. Not only they are all breathtakingly beautiful, with amazing variation of colors, they are scientifically accurate, revealing the molecular structure of a crystallized drink.

How are these images obtained? With polarized microscopy, which belongs to the optical microscopy family. The process uses polarized light to illuminate a sample (polarization is the property of an electromagnetic wave, such as light, to oscillate in a certain orientation). A variety of natural and synthetic materials, including polymers, can polarize light. The polarization can be linear, circular or elliptical, in either a clockwise or counterclockwise direction, depending in the properties of the polarizer. Most people are familiar with polarizing materials used in sunglasses, photography filters, and LCD displays. Polarized light is often used in material birefringence analysis for stress analysis.

Polarized light microscopy allows you to see the anisotropic character of a sample. The material is anisotropic if it has different physical properties in different directions. A polarized light microscope has a polarizer positioned before the light reaches the sample, and an analyzer, which is technically a second polarizer, between the sample and the observer (or the camera). The resulting image is obtained through the interaction of polarized light source and an anisotropic sample, in this case, crystalized beverages. Since most of the beverages are multicomponent mixes, the components tend to separate during crystallization, resulting in anisotropic films that are seen as fantastic, multicolor images.

Polarized light microscopy is used to analyze natural and synthetic materials, such as minerals, composites, fibers, ceramics, polymers, polymer films, wood, biological polymers, and tissue samples, and is a popular method in geology, material science, life sciences, and medicine. Turning it into art is certainly a brilliant idea, which might not only appeal to our senses, but also popularize science and share the excitement and awe with everyone.

Image by pilens/123RF.
Source: BevShots, bevshots.com.
Source: “Introduction to Polarized Light Microscopy,” Nikon, microscopyu.com.
Video: About BevShots, by BevShotsMedia, YouTube.com

Molly Shannon, Cupcakes, Alexander Fleming … and Megan

Megan Evans of PSI.

Megan Evans, quality control manager at Polymer Solutions.

 

Join us for a chat with…

Megan Evans,
Quality Assurance Manager

How long have you worked at PSI and what did you do before?

I’ve worked at PSI for 22 months. Prior to my job here, I worked at a consumer pet products company formulating shampoo and other companion animal products. Before that, I worked for a company that manufactured medical diagnostics. I spent 3 years in R&D, where I worked primarily on DNA extraction and PCR [polymerase chain reaction]. I spent another 2 years in Quality Assurance, where I learned a lot of quality assurance/quality control audit techniques.

Walk me through a typical day for you at PSI. Do you think anything you do would surprise people?

Well, there really isn’t a “typical” day. Generally speaking, my job is to help document corrective/preventive actions, maintain equipment qualification reports, equipment calibration records, and assist in writing work instructions. I also improve current systems that handle chemicals used for material testing. 

What’s a common misconception about the work you do, and why do you think that is?

I think a lot of people perceive quality assurance as over-the-top documentation and rightfully so. I think that there are times when quality systems are set up in a way that doesn’t consider the actual user/doer of the system. That can result in unnecessary redundancies. Since I have been a doer of systems in the past, it is easier for me to use past experience and determine what our laboratory staff can reasonably do to meet the requirements/regulations.

What’s been your favorite project at PSI so far, and why?

My favorite “project” has been bringing the equipment qualification documentation system under control for the chromatography lab. When I first started, the labs were maintaining cumbersome documentation, which took time away from testing. I developed a system that allows the technicians to perform the testing, and the quality department, in collaboration with the lab manager, handles the documentation. I think this is my favorite because I was able to take an existing system and make it streamlined, easy, and more robust while reducing the amount of work the lab had to do. Not to mention the fact that our client auditors like the current system we have in place :)

What’s the weirdest thing you’ve ever done at PSI?

If by weird, you mean awesome, I would have to say the day I brought in cupcakes and it turned into an experiment on photo-bleaching. Who knew cupcakes purchased from the local grocery store could turn in to an experiment in food dyes and the effects of light?

PSI prides itself of accepting new challenges. What project(s) have challenged you and given you satisfaction upon completion?

Our Full Assessment from LAB was this past May. This was a major challenge for me because I had never set in on a full assessment before, let alone been the lead on the audit preparation. I learned a lot about the way LAB accepts documentation and how much work goes into the preparation for a three-day audit.

If someone made a TV show or film about PSI, who would you want to play you, and why?

Even though we aren’t the same age, I would have to say Molly Shannon. I have always found her hilarious. I can remember thinking how funny she was when I watched her on Saturday Night Live. I think that she would be someone who could make my job in Quality highly entertaining.

Thinking back on great scientists in history … who is your favorite, and why?

Alexander Fleming is one of my favorites. His discovery of penicillin was an accident and that discovery had a huge impact on our society. I feel like his accidental discovery is an example of how awesome the world we live in really is. I also think that his lesson should teach us to be more accepting of accidents because not everything that comes from a perceived mistake or mishap is a bad thing.

What do you do for fun outside of work? Does it relate to what you do during the week?

In the words of a famous pop group, I workout. :)

Seriously, I have really grown to love road biking with my husband and friends. I’m currently training for a triathlon so it feels like I am constantly swimming, biking, running, or training.

I enjoy spending time spoiling my dog, Winston.

I also enjoy spending time with family and friends.

I feel like all of the things are related to what I do during the week because training for this triathlon and working out challenges me physically and mentally. My family, friends, and especially my husband inspire me push myself to new limits. Because of the support system I have, I will be able to complete this challenge which is how I feel about working at PSI. The people that I work with inspire me to work harder and push through the challenges. We work hard but we also play hard, and that is what makes it all worth it.