Biosensors

750 KiB

Open AccessArticle

Dielectrophoresis Aligned Single-Walled Carbon Nanotubes as pH Sensors

by Pengfei Li, Caleb M. Martin, Kan Kan Yeung and Wei Xue

Biosensors 2011, 1(1), 23-35; https://doi.org/10.3390/bios1010023 - 31 Jan 2011

Cited by 53 | Viewed by 12729

Here we report the fabrication and characterization of pH sensors using aligned single-walled carbon nanotubes (SWNTs). The SWNTs are dispersed in deionized (DI) water after chemical functionalization and filtration. They are deposited and organized on silicon substrates with the dielectrophoresis process. Electrodes with “teeth”-like patterns—fabricated with photolithography and wet etching—are used to generate concentrated electric fields and strong dielectrophoretic forces for the SWNTs to deposit and align in desired locations. The device fabrication is inexpensive, solution-based, and conducted at room temperature. The devices are used as pH sensors with the electrodes as the testing pads and the dielectrophoretically captured SWNTs as the sensing elements. When exposed to aqueous solutions with various pH values, the SWNTs change their resistance accordingly. The SWNT-based sensors demonstrate a linear relationship between the sensor resistance and the pH values in the range of 5–9. The characterization of multiple sensors proves that their pH sensitivity is highly repeatable. The real-time data acquisition shows that the sensor response time depends on the pH value, ranging from 2.26 s for the pH-5 solution to 23.82 s for the pH-9 solution. The long-term stability tests illustrate that the sensors can maintain their original sensitivity for a long period of time. The simple fabrication process, high sensitivity, and fast response of the SWNT-based sensors facilitate their applications in a wide range of areas. Full article

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227 KiB

Open AccessArticle

Nonlinear Dielectric Spectroscopy as an Indirect Probe of Metabolic Activity in Thylakoid Membrane

by Jie Fang, Akilan Palanisami, Kimal Rajapakshe, William R. Widger and John H. Miller, Jr.

Biosensors 2011, 1(1), 13-22; https://doi.org/10.3390/bios1010013 - 31 Jan 2011

Cited by 3 | Viewed by 6269

Abstract

Nonlinear dielectric spectroscopy (NDS) is a non-invasive probe of cellular metabolic activity with potential application in the development of whole-cell biosensors. However, the mechanism of NDS interaction with metabolic membrane proteins is poorly understood, partly due to the inherent complexity of single cell organisms. Here we use the light-activated electron transport chain of spinach thylakoid membrane as a model system to study how NDS interacts with metabolic activity. We find protein modification, as opposed to membrane pump activity, to be the dominant source of NDS signal change in this system. Potential mechanisms for such protein modifications include reactive oxygen species generation and light-activated phosphorylation. Full article

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57 KiB

Open AccessArticle

BioMEMS and Lab-on-a-Chip Course Education at West Virginia University

by Yuxin Liu

Biosensors 2011, 1(1), 4-12; https://doi.org/10.3390/bios1010004 - 20 Jan 2011

Cited by 3 | Viewed by 7859

Abstract

With the rapid growth of Biological/Biomedical MicroElectroMechanical Systems (BioMEMS) and microfluidic-based lab-on-a-chip (LOC) technology to biological and biomedical research and applications, demands for educated and trained researchers and technicians in these fields are rapidly expanding. Universities are expected to develop educational plans to address these specialized needs in BioMEMS, microfluidic and LOC science and technology. A course entitled BioMEMS and Lab-on-a-Chip was taught recently at the senior undergraduate and graduate levels in the Department of Computer Science and Electrical Engineering at West Virginia University (WVU). The course focused on the basic principles and applications of BioMEMS and LOC technology to the areas of biomedicine, biology, and biotechnology. The course was well received and the enrolled students had diverse backgrounds in electrical engineering, material science, biology, mechanical engineering, and chemistry. Student feedback and a review of the course evaluations indicated that the course was effective in achieving its objectives. Student presentations at the end of the course were a highlight and a valuable experience for all involved. The course proved successful and will continue to be offered regularly. This paper provides an overview of the course as well as some development and future improvements. Full article

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24 KiB

Open AccessEditorial

Welcome to Biosensors: A New Open-Access Journal

by Jeffrey D. Newman

Biosensors 2011, 1(1), 1-3; https://doi.org/10.3390/bios1010001 - 19 Jan 2011

Viewed by 4891

Abstract

The journal Biosensors has been started as a peer-reviewed, open access journal. As editors, we believe that it will fulfill an important role in the community of researchers and developers in the field of biosensors. The addition of a “free access” journal to the existing, high quality publications in this field is something that we believe is very important in a field which is now so entwined with commercial activity and where researchers aim, not only at academic research, but on the development of products at a potentially massive scale. For these researchers, it is important that they can publish their results in a journal that guarantees quality that comes from peer-review, but that at the same time breaks the traditional boundaries of academic journals which need a subscription or a pay-per-view option to access the published data. [...] Full article

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Biosensors, Volume 1, Issue 1 (March 2011) – 4 articles , Pages 1-35

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