Navigation Links
Imperfections may improve graphene sensors

Although they found that graphene makes very good chemical sensors, researchers at the University of Illinois at Urbana-Champaign have discovered an unexpected "twist"that the sensors are better when the graphene is "worse"more imperfections improved performance.

"This is quite the opposite of what you would want for transistors, for example," explained Eric Pop, an assistant professor of electrical and computer engineering and a member of the interdisciplinary research team. "Finding that the less perfect they were, the better they worked, was counter intuitive at first."

The research group, which includes researchers from both chemical engineering and electrical engineering, and from a startup company, Dioxide Materials, reported their results in the November 23, 2011 issue of Advanced Materials.

"The objective of this work was to understand what limits the sensitivity of simple, two-terminal graphene chemiresistors, and to study this in the context of inexpensive devices easily manufactured by chemical vapor deposition (CVD)," stated lead authors Amin Salehi-Khojin and David Estrada.

The researchers found that the response of graphene chemiresistors depends on the types and geometry of their defects.

"Nearly-pristine graphene chemiresistors are less sensitive to analyte molecules because adsorbates bind to point defects, which have low resistance pathways around them," noted Salehi-Khojin, a research scientist at Dioxide Materials and post-doctoral research associate in the Department of Chemical and Biomolecular Engineering (ChemE) at Illinois. "As a result, adsorption at point defects only has a small effect on the overall resistance of the device. On the other hand, micrometer-sized line defects or continuous lines of point defects are different because no easy conduction paths exist around such defects, so the resistance change after adsorption is significant."

"This can lead to better and cheaper gas sensors for a variety of applications such as energy, homeland security and medical diagnostics" said Estrada who is a doctoral candidate in the Department of Electrical and Computer Engineering.

According to the authors, the two-dimensional nature of defective, CVD-grown graphene chemiresistors causes them to behave differently than carbon nanotube chemiresistors. This sensitivity is further improved by cutting the graphene into ribbons of width comparable to the line defect dimensions, or micrometers in this study.

"What we determined is that the gases we were sensing tend to bind to the defects," Pop said. "Surface defects in graphene are either point-, wrinkle-, or line-like. We found that the points do not matter very much and the lines are most likely where the sensing happens."

"The graphene ribbons with line defects appear to offer superior performance as graphene sensors," said ChemE professor emeritus and Dioxide Materials CEO Richard Masel. "Going forward, we think we may be able engineer the line defects to maximize the material's sensitivity. This novel approach should allow us to produce inexpensive and sensitive chemical sensors with the performance better than that of carbon nanotube sensors."


Contact: Eric Pop
University of Illinois College of Engineering

Related biology technology :

1. Imperfections may improve graphene sensors
2. Self-assembling polymer arrays improve data storage potential
3. Beaumont Doctors Invention Improves Cataract Surgery Outcomes
4. Early-Bird Registration Ends this Week for 10th Annual Quality Excellence Conference: How Process Improvement Leaders Produce Profits in Recessions
5. Carilion Clinic Invests in Sight Saving Technology to Improve Patient Care: Carilion Clinic Teams Up with Retasure
6. Germicidal UVC Lights Improve Clinical Pregnancy Rates for IVF Lab, New Study Finds
7. Sanofi Aventis : New Study Results Support the "Basal Plus" Strategy With LANTUS(R) and APIDRA(R) to Improve Blood Sugar Control in Patients With Type 2 Diabetes
8. Enobia Pharma Presents PreClinical Data Showing ENB-0040 Significantly Improved Survival and Healed Skeletal Manifestations of Severe Hypophosphatasia in Mice
9. Global Psychiatrists Unite to Improve Services in Mental Health
10. Kelly Osbourne and International Health Groups Call for Improved Education on Choices and Usage of Contraception
11. Commonwealth Care Alliance Selects Casenet To Unify Patient Information and Improve Care for Massachusetts Members
Post Your Comments:
(Date:11/27/2015)... 27, 2015 ... of companion diagnostics is one of the ... with pharmaceutical companies and diagnostic manufacturers working ... . --> ... on global cancer biomarkers market spread across ...
(Date:11/25/2015)... India , November 26, 2015 ... The Global Biobanking Market 2016 - 2020 report ... by maintaining integrity and quality in long-term samples, ... enabling long-term cost-effectiveness. Automation minimizes manual errors such ... the technical efficiency. Further, it plays a vital ...
(Date:11/25/2015)... BRUSSELS , November 25, 2015 ... in cat and human plaque and pave the way for ... health problems in cats     ... the most commonly diagnosed health problems in cats, yet relatively ... until now. Two collaborative studies have been conducted by researchers ...
(Date:11/25/2015)... 2015 /PRNewswire/ - Aeterna Zentaris Inc. (NASDAQ:  AEZS; TSX: ... prospects remain fundamentally strong and highlights the following ... received DSMB recommendation to continue the ZoptEC Phase ... the final interim efficacy and safety data ... men with heavily pretreated castration- and Taxane-resistant prostate ...
Breaking Biology Technology:
(Date:11/16/2015)... , Nov 16, 2015  Synaptics Inc. (NASDAQ: ... interface solutions, today announced expansion of its TDDI ... touch controller and display driver integration (TDDI) ... smartphones. These new TDDI products add to the ... resolution), TD4302 (WQHD resolution), and TD4322 (FHD resolution) ...
(Date:11/12/2015)... 2015   Growing need for low-cost, easy ... been paving the way for use of biochemical ... analytes in clinical, agricultural, environmental, food and defense ... in medical applications, however, their adoption is increasing ... continuous emphasis on improving product quality and growing ...
(Date:11/10/2015)... 10, 2015 About signature ... helps to identify and verify the identity of ... as the secure and accurate method of authentication ... particular individual because each individual,s signature is highly ... when dynamic signature of an individual is compared ...
Breaking Biology News(10 mins):