Tag Archives: biosensor

Spinach and plant nanobionics

Who knew that spinach leaves could be turned into electronic devices? The answer is: engineers at the Massachusetts Institute of Technology, according to an Oct. 31, 2016 news item on phys.org,

Spinach is no longer just a superfood: By embedding leaves with carbon nanotubes, MIT engineers have transformed spinach plants into sensors that can detect explosives and wirelessly relay that information to a handheld device similar to a smartphone.

This is one of the first demonstrations of engineering electronic systems into plants, an approach that the researchers call “plant nanobionics.”

An Oct. 31, 2016 MIT news release (also on EurekAlert), which originated the news item, describes the research further (Note: Links have been removed),

“The goal of plant nanobionics is to introduce nanoparticles into the plant to give it non-native functions,” says Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT and the leader of the research team.

In this case, the plants were designed to detect chemical compounds known as nitroaromatics, which are often used in landmines and other explosives. When one of these chemicals is present in the groundwater sampled naturally by the plant, carbon nanotubes embedded in the plant leaves emit a fluorescent signal that can be read with an infrared camera. The camera can be attached to a small computer similar to a smartphone, which then sends an email to the user.

“This is a novel demonstration of how we have overcome the plant/human communication barrier,” says Strano, who believes plant power could also be harnessed to warn of pollutants and environmental conditions such as drought.

Strano is the senior author of a paper describing the nanobionic plants in the Oct. 31 [2016] issue of Nature Materials. The paper’s lead authors are Min Hao Wong, an MIT graduate student who has started a company called Plantea to further develop this technology, and Juan Pablo Giraldo, a former MIT postdoc who is now an assistant professor at the University of California at Riverside.

Environmental monitoring

Two years ago, in the first demonstration of plant nanobionics, Strano and former MIT postdoc Juan Pablo Giraldo used nanoparticles to enhance plants’ photosynthesis ability and to turn them into sensors for nitric oxide, a pollutant produced by combustion.

Plants are ideally suited for monitoring the environment because they already take in a lot of information from their surroundings, Strano says.

“Plants are very good analytical chemists,” he says. “They have an extensive root network in the soil, are constantly sampling groundwater, and have a way to self-power the transport of that water up into the leaves.”

Strano’s lab has previously developed carbon nanotubes that can be used as sensors to detect a wide range of molecules, including hydrogen peroxide, the explosive TNT, and the nerve gas sarin. When the target molecule binds to a polymer wrapped around the nanotube, it alters the tube’s fluorescence.

In the new study, the researchers embedded sensors for nitroaromatic compounds into the leaves of spinach plants. Using a technique called vascular infusion, which involves applying a solution of nanoparticles to the underside of the leaf, they placed the sensors into a leaf layer known as the mesophyll, which is where most photosynthesis takes place.

They also embedded carbon nanotubes that emit a constant fluorescent signal that serves as a reference. This allows the researchers to compare the two fluorescent signals, making it easier to determine if the explosive sensor has detected anything. If there are any explosive molecules in the groundwater, it takes about 10 minutes for the plant to draw them up into the leaves, where they encounter the detector.

To read the signal, the researchers shine a laser onto the leaf, prompting the nanotubes in the leaf to emit near-infrared fluorescent light. This can be detected with a small infrared camera connected to a Raspberry Pi, a $35 credit-card-sized computer similar to the computer inside a smartphone. The signal could also be detected with a smartphone by removing the infrared filter that most camera phones have, the researchers say.

“This setup could be replaced by a cell phone and the right kind of camera,” Strano says. “It’s just the infrared filter that would stop you from using your cell phone.”

Using this setup, the researchers can pick up a signal from about 1 meter away from the plant, and they are now working on increasing that distance.

Michael McAlpine, an associate professor of mechanical engineering at the University of Minnesota, says this approach holds great potential for engineering not only sensors but many other kinds of bionic plants that might receive radio signals or change color.

“When you have manmade materials infiltrated into a living organism, you can have plants do things that plants don’t ordinarily do,” says McAlpine, who was not involved in the research. “Once you start to think of living organisms like plants as biomaterials that can be combined with electronic materials, this is all possible.”

“A wealth of information”

In the 2014 plant nanobionics study, Strano’s lab worked with a common laboratory plant known as Arabidopsis thaliana. However, the researchers wanted to use common spinach plants for the latest study, to demonstrate the versatility of this technique. “You can apply these techniques with any living plant,” Strano says.

So far, the researchers have also engineered spinach plants that can detect dopamine, which influences plant root growth, and they are now working on additional sensors, including some that track the chemicals plants use to convey information within their own tissues.

“Plants are very environmentally responsive,” Strano says. “They know that there is going to be a drought long before we do. They can detect small changes in the properties of soil and water potential. If we tap into those chemical signaling pathways, there is a wealth of information to access.”

These sensors could also help botanists learn more about the inner workings of plants, monitor plant health, and maximize the yield of rare compounds synthesized by plants such as the Madagascar periwinkle, which produces drugs used to treat cancer.

“These sensors give real-time information from the plant. It is almost like having the plant talk to us about the environment they are in,” Wong says. “In the case of precision agriculture, having such information can directly affect yield and margins.”

Once getting over the excitement, questions spring to mind. How could this be implemented? Is somebody  going to plant a field of spinach and then embed the leaves so they can detect landmines? How will anyone know where to plant the spinach? And on a different track, is this spinach edible? I suspect that if spinach can be successfully used as a sensor, it might not be for explosives but for pollution as the researchers suggest.

Here’s a link to and a citation for the paper,

Nitroaromatic detection and infrared communication from wild-type plants using plant nanobionics by Min Hao Wong, Juan P. Giraldo, Seon-Yeong Kwak, Volodymyr B. Koman, Rosalie Sinclair, Tedrick Thomas Salim Lew, Gili Bisker, Pingwei Liu, & Michael S. Strano. Nature Materials (2016) doi:10.1038/nmat4771 Published online 31 October 2016

This paper is behind a paywall.

The last posting here which featured Strano’s research is in an Aug. 25, 2015 piece about carbon nanotubes and medical sensors.

Device detects molecules associated with neurodegenerative diseases

It’s nice to get notice of research in South America, an area for which I rarely stumble across any news releases. Brazilian researchers have developed a device that could help diagnose neurodegenerative diseases such as Alzheimer’s and and Parkinson’s as well as some cancers according to a May 20, 2016 news item on Nanotechnology Now,

A biosensor developed by researchers at the National Nanotechnology Laboratory (LNNano) in Campinas, São Paulo State, Brazil, has been proven capable of detecting molecules associated with neurodegenerative diseases and some types of cancer.

The device is basically a single-layer organic nanometer-scale transistor on a glass slide. It contains the reduced form of the peptide glutathione (GSH), which reacts in a specific way when it comes into contact with the enzyme glutathione S-transferase (GST), linked to Parkinson’s, Alzheimer’s and breast cancer, among other diseases. The GSH-GST reaction is detected by the transistor, which can be used for diagnostic purposes.

The project focuses on the development of point-of-care devices by researchers in a range of knowledge areas, using functional materials to produce simple sensors and microfluidic systems for rapid diagnosis.

A May 19, 2016 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) press release, which originated the news item, provides more detail,

“Platforms like this one can be deployed to diagnose complex diseases quickly, safely and relatively cheaply, using nanometer-scale systems to identify molecules of interest in the material analyzed,” explained Carlos Cesar Bof Bufon, Head of LNNano’s Functional Devices & Systems Lab (DSF) and a member of the research team for the project, whose principal investigator is Lauro Kubota, a professor at the University of Campinas’s Chemistry Institute (IQ-UNICAMP).

In addition to portability and low cost, the advantages of the nanometric biosensor include its sensitivity in detecting molecules, according to Bufon.

“This is the first time organic transistor technology has been used in detecting the pair GSH-GST, which is important in diagnosing degenerative diseases, for example,” he explained. “The device can detect such molecules even when they’re present at very low levels in the examined material, thanks to its nanometric sensitivity.” A nanometer (nm) is one billionth of a meter (10-9 meter), or one millionth of a millimeter.

The system can be adapted to detect other substances, such as molecules linked to different diseases and elements present in contaminated material, among other applications. This requires replacing the molecules in the sensor with others that react with the chemicals targeted by the test, which are known as analytes.

The team is working on paper-based biosensors to lower the cost even further and to improve portability and facilitate fabrication as well as disposal.

The challenge is that paper is an insulator in its usual form. Bufon has developed a technique to make paper conductive and capable of transporting sensing data by impregnating cellulose fibers with polymers that have conductive properties.

The technique is based on in situ synthesis of conductive polymers. For the polymers not to remain trapped on the surface of the paper, they have to be synthesized inside and between the pores of the cellulose fibers. This is done by gas-phase chemical polymerization: a liquid oxidant is infiltrated into the paper, which is then exposed to monomers in the gas phase. A monomer is a molecule of low molecular weight capable of reacting with identical or different molecules of low molecular weight to form a polymer.

The monomers evaporate under the paper and penetrate the pores of the fibers at the submicrometer scale. Inside the pores, they blend with the oxidant and begin the polymerization process right there, impregnating the entire material.

The polymerized paper acquires the conductive properties of the polymers. This conductivity can be adjusted by manipulating the element embedded in the cellulose fibers, depending on the application for which the paper is designed. Thus, the device can be electrically conductive, allowing current to flow without significant losses, or semiconductive, interacting with specific molecules and functioning as a physical, chemical or electrochemical sensor.

There’s no mention of a published paper.

Monitoring your saliva via mouth guard and smart phone

I first came across the notion that saliva instead of blood and urine could be used to assess and monitor health in a presentation abstract for the 2004 American Association for the Advancement of Science (AAAS) annual meeting held in Seattle, Washington (as per my Feb. 15, 2011 posting). There have been a few ‘saliva’ health monitoring projects mentioned here over the years but this proof-of-concept version seems like it has the potential to get to the marketplace. An August 31, 2015 news item on Nanowerk features a ‘saliva’ health monitoring project from the University of California at San Diego (UCSD),

Engineers at the University of California, San Diego, have developed a mouth guard that can monitor health markers, such as lactate, cortisol and uric acid, in saliva and transmit the information wirelessly to a smart phone, laptop or tablet.
The technology, which is at a proof-of-concept stage, could be used to monitor patients continuously without invasive procedures, as well as to monitor athletes’ performance or stress levels in soldiers and pilots. In this study, engineers focused on uric acid, which is a marker related to diabetes and to gout. Currently, the only way to monitor the levels of uric acid in a patient is to draw blood.

An August 31, 2015 UCSD news release (also on EurekAlert), which originated the news item, describes the research and the mouth guard in more detail,

In this study, researchers showed that the mouth guard sensor could offer an easy and reliable way to monitor uric acid levels. The mouth guard has been tested with human saliva but hasn’t been tested in a person’s mouth.

Researchers collected saliva samples from healthy volunteers and spread them on the sensor, which produced readings in a normal range. Next, they collected saliva from a patient who suffers from hyperuricemia, a condition characterized by an excess of uric acid in the blood. The sensor detected more than four times as much uric acid in the patient’s saliva than in the healthy volunteers.

The patient also took Allopurinol, which had been prescribed by a physician to treat their condition. Researchers were able to document a drop in the levels of uric acid over four or five days as the medication took effect. In the past, the patient would have needed blood draws to monitor levels and relied instead on symptoms to start and stop his medication.

Fabrication and design

Wang’s team created a screen-printed sensor using silver, Prussian blue ink and uricase, an enzyme that reacts with uric acid. Because saliva is extremely complex and contains many different biomarkers, researchers needed to make sure that the sensors only reacted with the uric acid. Nanoengineers set up the chemical equivalent of a two-step authentication system. The first step is a series of chemical keyholes, which ensures that only the smallest biochemicals get inside the sensor. The second step is a layer of uricase trapped in polymers, which reacts selectively with uric acid. The reaction between acid and enzyme generates hydrogen peroxide, which is detected by the Prussian blue ink.  That information is then transmitted to an electronic board as electrical signals via metallic strips that are part of the sensor.

The electronic board, developed by Mercier’s team, uses small chips that sense the output of the sensors, digitizes this output and then wirelessly transmits data to a smart phone, tablet or laptop. The entire electronic board occupies an area slightly larger than a U.S. penny.

Next steps

The next step is to embed all the electronics inside the mouth guard so that it can actually be worn. Researchers also will have to test the materials used for the sensors and electronics to make sure that they are indeed completely biocompatible. The next iteration of the mouth guard is about a year out, Mercier estimates.

“All the components are there,” he said. “It’s just a matter of refining the device and working on its stability.”

Wang and Mercier lead the Center for Wearable Sensors at UC San Diego, which has made a series of breakthroughs in the field, including temporary tattoos that monitor glucose, ultra-miniaturized energy-processing chips and pens filled with high-tech inks for Do It Yourself chemical sensors.

Here’s a link to and a citation for the paper,

Wearable salivary uric acid mouthguard biosensor with integrated wireless electronics by Jayoung Kim, Somayeh Imani, William R. de Araujo, Julian Warchall, Gabriela Valdés-Ramírez, Thiago R.L.C. Paixão, Patrick P. Mercier, & Joseph Wang. Biosensors and Bioelectronics Volume 74, 15 December 2015, Pages 1061–1068 doi:10.1016/j.bios.2015.07.039

This paper is behind a paywall.

Here’s an image of UCSD’s proposed mouth guard,

The mouth guard sensor offers an easy and reliable way to monitor uric acid levels in human saliva. Credit: Jacobs School of Engineering, UC San Diego

The mouth guard sensor offers an easy and reliable way to monitor uric acid levels in human saliva. Credit: Jacobs School of Engineering, UC San Diego

Nano-Bio Manufacturing Consortium’s request for proposals (RFPs) on human performance monitoring platforms

The requested human performance monitor platform RFPs are for a US Air Force Research Laboratory (AFRL) project being managed by the Nano-Bio Manufacturing Consortium (NBMC), according to a July 17, 2013 news item on Nanowerk,

The Nano-Bio Manufacturing Consortium (NBMC) has released its first Request for Proposals (RFP) focused on developing a technology platform for Human Performance Monitors for military and civilian personnel in high stress situations such as pilots, special operations personnel, firefighters, and trauma care providers. Organized by FlexTech Alliance under a grant from the U.S. Air Force Research Laboratory (AFRL) the RFP comes only 3 month since the group officially formed its technical and leadership teams. The consortium members, working with AFRL, issued this RFP to focus on component development and integration for a lightweight, low-cost, conformal and wearable patch.

The July 17, 2013 NBMC news release, which originated the news item, offers more about this patch/monitor,

The heart of this new patch will be a biosensor device to measure chemicals, called biomarkers, in human sweat.  These biomarkers can provide early warnings of performance issues such as stress, fatigue, vigilance or organ damage.  The platform will contain the sensor, a microfluidic system that delivers sweat to the sensor, printed and hybrid control electronics, interconnects, a power supply, wireless communication, and software – all on a flexible substrate that is comfortable to wear.

“An aircraft has numerous sensors which take over 1500 measurements per second to monitor its condition in flight, whereas the most critical part – the pilot – has no monitors,” Malcolm Thompson, chief executive officer of NBMC stated.  “We are working quickly and efficiently to coordinate the expertise being generated at an array of companies, government labs and academic centers.  NBMC’s goal is to establish this technology chain to more rapidly develop products and manufacturing approaches for the Air Force and commercial markets.”

I gather the reasoning is that we should be able to monitor human beings just as we do equipment and machines.

The news release also offers information about the consortium partners,

Initial consortium membership includes a wide range of organizations.  Fortune 500 technology leaders include General Electric, Lockheed Martin, and DuPont Teijin Films.  More entrepreneurial organizations include PARC (a Xerox Company), MC 10, Soligie, American Semiconductor, Brewer Science and UES.  They are joined by the Air Force Research Laboratory and university leaders such as Cornell University, University of Massachusetts Amherst Center for Hierarchical Manufacturing, University of Arizona Center for Integrative Medicine, UC San Diego, University of Cincinnati, Binghamton University, Johns Hopkins University, Northeastern University NSF Nanoscale Science and Engineering Center for High-rate Nano-manufacturing, and Arizona State University.

The NBMC solicitation was posted July 10, 2013 on this page,


Request for Proposals Issued: July 10th, 2013

Proposals Due Date: August 9th, 2013 – 5:00 PM PDT

You can find the 9pp RFP here.

I’ve decided to include this description of the thinking that underlies the consortium, from the NBMC Nano-Bio Manufacturing webpage,

The field of nano-biotechnology is advancing rapidly, with many important discoveries and potential applications being identified.  Much of this work is taking place in academia and advanced research labs around the globe.  Once an application is identified, however, the road is still long to making it available to the markets in need.  One of the final steps on that road is understanding how to manufacture in high volume and the lowest cost.  Often this is the defining decision on whether the product even gets to that market.

With new nano-bio technology solutions, the challenges to produce in volume at low-cost are entirely new to many in the field.  New materials, new substrates, new equipment, and unknown properties are just a few of the hurdles that no one organization has been able to overcome.

To address these challenges, FlexTech Alliance, in collaboration with a nationwide group of partners, has formed a Nano-Bio Manufacturing Consortium (NBMC) for the U.S. Air Force Research Laboratory (AFRL). The mission of this partnership is to bring together leading scientists, engineers, and business development professionals from industry and universities in order to work collaboratively in a consortium, and to mature an integrated suite of nano-bio manufacturing technologies to transition to industrial manufacturing.

Initial activities focus on AFRL/ DoD priorities, e.g., physiological readiness and human performance monitoring. Specifically, NBMC matures nano-bio manufacturing technologies to create an integrated suite of reconfigurable and digitized fabrication methods that are compatible with biological and nanoparticle materials and to transition thin film, mechanically compliant device concepts through a foundry-like manufacturing flow.

The long-term vision is that NBMC operates at the confluence of four core emerging disciplines: nanotechnology, biotechnology, advanced (additive) manufacturing, and flexible electronics. The convergence of these disparate fields enables advanced sensor architectures for real-time, remote physiological and health/medical monitoring.

[downloaded from http://www.nbmc.org/nanobiomanufacturing/nbm_intro/]

[downloaded from http://www.nbmc.org/nanobiomanufacturing/nbm_intro/]

It seems to me that human beings are increasingly being viewed as just another piece of equipment.

Home pregnancy tests inspire simple diagnostics containing gold nanoparticles

PhD student Kyryl Zagorovsky and Professor Warren Chan of the University of Toronto’s Institute of Biomaterials and Biomedical Engineering (IBBME) have created a rapid diagnostic biosensor according to a Feb. 28, 2013 news item on phys.org,

A diagnostic “cocktail” containing a single drop of blood, a dribble of water, and a dose of DNA powder with gold particles could mean rapid diagnosis and treatment of the world’s leading diseases in the near future. …

The recent winner of the NSERC E.W.R. Steacie Memorial Fellowship, Professor Chan and his lab study nanoparticles: in particular, the use of gold particles in sizes so small that they are measured in the nanoscale. Chan and his group are working on custom-designing nanoparticles to target and illuminate cancer cells and tumours, with the potential of one day being able to deliver drugs to cancer cells.

But it’s a study recently published in Angewandte Chemie that’s raising some interesting questions about the future of this relatively new frontier of science.

Zagorovsky’s rapid diagnostic biosensor will allow technicians to test for multiple diseases at one time with one small sample, and with high accuracy and sensitivity. The biosensor relies upon gold particles in much the same vein as your average pregnancy test. With a pregnancy test, gold particles turn the test window red because the particles are linked with an antigen that detects a certain hormone in the urine of a pregnant woman.

(Until now, I’d never thought about how a pregnancy test actually works and always assumed it was similar to a litmus paper test of acid.) The University of Toronto’s Feb. 28, 2013 news release, which originated the news item, describes the technology in more detail,

Currently, scientists can target a particular disease by linking gold particles with DNA strands. When a sample containing the disease gene (e.g., Malaria) is present, it clumps the gold particles, turning the sample blue.

Rather than clumping the particles together, Zagorovsky immerses the gold particles in a DNA-based enzyme solution (DNA-zyme) that, when the disease gene is introduced, ‘snip’ the DNA from the gold particles, turning the sample red.

“It’s like a pair of scissors,” said Zagorovsky. “The target gene activates the scissors that cut the DNA links holding gold particles together.”

The advantage is that far less of the gene needs to be present for the solution to show noticeable colour changes, amplifying detection. A single DNA-zyme can clip up to 600 ‘links’ between the target genes.

Just a single drop from a biological sample such as saliva or blood can potentially be tested in parallel, so that multiple diseases can be tested in one sitting.

But the team has also demonstrated that [it] can transform the testing solution into a powder, making it light and far easier to ship than solutions, which degrade over time. Powder can be stored for years at a time, and offers hope that the technology can be developed into efficient, cheap, over-the-counter tests for diseases such as HIV and malaria for developing countries, where access to portable diagnostics is a necessity. [emphases mine]

I think the fact that the testing solution can be made into powder is exciting news. Medical technologies can be wonderful but if they require special handling and training (e.g., a standard vaccine is in a solution which needs to be refrigerated [that’s expensive in some parts of the world] and someone who is specially trained has to administer the injection) then they’re confined to the few who have access and can afford it.

Here’s a citation and a link to the researchers’ paper,

A Plasmonic DNAzyme Strategy for Point-of-Care Genetic Detection of Infectious Pathogens by Kyryl Zagorovsky, and Dr. Warren C. W. Chan. Angewandte Chemie International Edition DOI: 10.1002/anie.201208715 Article first published online: 10 FEB 2013

Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This article is behind a paywall.

ETA Mar. 1, 2013 10:42 am PST: I made a quick change to the title. Hopefully this one makes more sense than the first one did.

Nanocanaries don’t die

It’s upsetting to think about the canaries in the mines singing to their heart’s content only to topple over and die when toxic gases make their presence felt during the mining process. The alternative, of course, is to sacrifice miners. Thankfully, choosing the lesser of two evils will no longer be necessary (actually, I don’t they’ve used canaries in quite a while) as scientists work on sensors that can detect any number of things not just toxic gases in the mines. The University of Massachusetts at Lowell is the latest to announce work on sensors (from the Nov. 15, 2012 news item on Nanowerk),

To detect the toxicity of engineered nanomaterials, such as carbon nanotubes, on living cells, electrical engineering Assoc. Prof. Joel Therrien — along with biology Prof. Susan Braunhut, chemistry Prof. Kenneth Marx and work environment Asst. Prof. Dhimiter Bello — has developed a “nanocanary,” the modern-day, high-tech equivalent of the canary in a coal mine that warned miners of dangerous buildups of toxic gases in the mine shaft.
The nanocanary is an ultrasensitive biosensor designed to continuously monitor tiny physiological changes in the live cells contained within it.

The Nov. 14, 2012 news release by Edwin L. Aguirre, which originated the news item, mentions a recent podcast by one of the researchers (Joel Therrien),

In a recent podcast produced by the Museum of Science in Boston, Therrien talked about the importance of studying how nano-sized particles affect human health and the environment as well as in the safe development of commercial nano products.

“Our biosensor has a wide range of applications, from testing for toxicity in nanomanufacturing to drug development and customized cancer therapeutics,” notes Therrien.

“In testing the toxicity of carbon nanotubes, for example, since the sensor can directly detect adverse effects on living cells, we are able to identify the threshold concentration at which carbon nanotubes lead to the cells’ death,” he explains. “The sensor can also be used to test the response of normal and cancerous cells to drug therapies. In the future, this technology may help guide oncologists in selecting the most appropriate drug for a cancer patient. We also see the potential for this to partially replace animals in testing drugs and other products.”

Therrien’s 16 min. podcast can be heard here.

I’ll cry if I want to—measuring glucose levels in your tears

If you look closely, you’ll see a tiny sensor beneath the eye. Inside there are nano-size biosensors which can detect your glucose levels in your tears (or sweat, if prefer). For a diabetic, checking glucose levels has to be done daily by pricking the skin to draw blood.

With this nano-sized biosensor, diabetes patients can measure their glucose levels with the fluid from the tears of their eyes. (copyright Fraunhofer IMS)

Sept. 4, 2012 news item on Nanowerk provides more details,

Pricking a finger everyday is just part of everyday life for many diabetes patients. A non-invasive measurement approach could release them from the constant pain of pin pricks. The linchpin is a biosensor engineered by Fraunhofer researchers: A tiny chip combines measurement and digital analysis – and can be radioed to a mobile device.

The Sept. 3, 2012 news release from Fraunhofer, an application-oriented research organization, provides more detail about the technology and its advantages,

The principle of measurement involves an electrochemical reaction that is activated with the aid of an enzyme. Glucose oxidase converts glucose into hydrogen peroxide (H2O2) and other chemicals whose concentration can be measured with a potentiostat. This measurement is used for calculating the glucose level. The special feature of this biosensor: the chip, measuring just 0.5 x 2.0 millimeters, can fit more than just the nanopotentiostat itself. Indeed, Fraunhofer researchers have attached the entire diagnostic system to it. “It even has an integrated analog digital converter that converts the electrochemical signals into digital data,” explains Tom Zimmermann, business unit manager at IMS. The biosensor transmits the data via a wireless interface, for example to a mobile receiver. Thus, the patient can keep a steady eye on his or her glucose level. “In the past, you used to need a circuit board the size of a half-sheet of paper,” says Zimmermann. “And you also had to have a driver. But even these things are no longer necessary with our new sensor.”

The minimal size is not the only thing that provides a substantial advantage over previous biosensors of this type. In addition, the sensor consumes substantially less power. Earlier systems required about 500 microamperes at five volts; now, it is less than 100 microamperes. That increases the durability of the system – allowing the patient to wear the sensor for weeks, or even months. The use of a passive system makes this durability possible. The sensor is able to send and receive data packages, but it can also be supplied with power through radio frequency.

The glucose sensor was engineered by the researchers at Noviosens, a Dutch medical technology firm. Since it can be manufactured so cost-effectively, it is best suited for mass production.

This looks pretty exciting. Of course, I’d still like to see find out the level of accuracy for this new way to measure glucose as compared to the current technique (no mention of clinical trials). Also, how do you affix the sensor to your skin? Is there a glue? Can you accidentally wash, wipe,  or knock your sensor off? Or, is it difficult to remove? For people who do choose to wear it beneath an eye, how does makeup affect the sensor?

Assuming that the accuracy is the same or better and that any pitfalls due to wearing a sensor have been addressed, I imagine the next hurdle will be scaling up production.

As for the ‘I’ll cry if I want to’ part of the headline for this piece, I have shamelessly borrowed [corrected 2:27 pm PDT, Sept. 5, 2012] from Lesley Gore’s 1963 hit, ‘I’s my party and I’ll cry if want to’. I’ve never loved the lyrics (for the most part) but the chorus has a haunting quality (as far as I’m concerned). Here is Lesley Gore,

Blood, tears, and urine for use in diagnostic tools

Frankly, I’d rather just spit into a cup or onto a slide for diagnostic tests than having to supply urine or have my blood drawn. I don’t think that day has arrived yet but scientists at Purdue University (Indiana, US) have made a breakthrough. From the Aug. 23, 2012 news item on ScienceDaily,

Researchers have created a new type of biosensor that can detect minute concentrations of glucose in saliva, tears and urine and might be manufactured at low cost because it does not require many processing steps to produce.

“It’s an inherently non-invasive way to estimate glucose content in the body,” said Jonathan Claussen, a former Purdue University doctoral student and now a research scientist at the U.S. Naval Research Laboratory. “Because it can detect glucose in the saliva and tears, it’s a platform that might eventually help to eliminate or reduce the frequency of using pinpricks for diabetes testing. We are proving its functionality.”

Claussen and Purdue doctoral student Anurag Kumar led the project, working with Timothy Fisher, a Purdue professor of mechanical engineering; D. Marshall Porterfield, a professor of agricultural and biological engineering; and other researchers at the university’s Birck Nanotechnology Center.

The originating Aug. 20, 2012 Purdue University news release by Emil Venere provides details as to how this biosensor works,

The sensor has three main parts: layers of nanosheets resembling tiny rose petals made of a material called graphene, which is a single-atom-thick film of carbon; platinum nanoparticles; and the enzyme glucose oxidase.

Each petal contains a few layers of stacked graphene. The edges of the petals have dangling, incomplete chemical bonds, defects where platinum nanoparticles can attach. Electrodes are formed by combining the nanosheet petals and platinum nanoparticles. Then the glucose oxidase attaches to the platinum nanoparticles. The enzyme converts glucose to peroxide, which generates a signal on the electrode.

“Typically, when you want to make a nanostructured biosensor you have to use a lot of processing steps before you reach the final biosensor product,” Kumar said. “That involves lithography, chemical processing, etching and other steps. The good thing about these petals is that they can be grown on just about any surface, and we don’t need to use any of these steps, so it could be ideal for commercialization.”

In addition to diabetes testing, the technology might be used for sensing a variety of chemical compounds to test for other medical conditions.

Here’s a representation of the ‘rose petal’ nanosheets,

These color-enhanced scanning electron microscope images show nanosheets resembling tiny rose petals. The nanosheets are key components of a new type of biosensor that can detect minute concentrations of glucose in saliva, tears and urine. The technology might eventually help to eliminate or reduce the frequency of using pinpricks for diabetes testing. (Purdue University photo/Jeff Goecker)
Download Photo

My most recent piece, prior to this, about less invasive diagnostic tests was this May 8, 2012 posting on a handheld diagnostic device that tests your breath for disease.