Silicon nanowire electrochemical sensors

Introduction

Lab-on-a-chip (LOC) microsystems for the detection of biomolecules at very low concentrations are becoming increasingly important for applications requiring high-throughput biomolecular analyses, such as protein arrays for basic molecular biology research, disease marker identification, and pharmaceutical drug screening. Techniques and methods used for protein arrays are improving, however, progress has been hindered by size and detection constraints. First, conventional protein arrays require relatively large sample volumes. One strategy for overcoming this problem is to significantly decrease the size and consequently the sample volume of the protein interaction assay, an ideal application of LOC. Secondly, the detection of protein and chemical pathogens (targets) is currently most commonly done using fluorescence detection of the probe-target binding. Although very sensitive, fluorescence detection suffers from the need to label the molecular target, which can lead to alterations in target-receptor interactions caused by conformational changes or steric hindrance induced by the label. The efficiency of labeling varies from protein to protein, making comparisons a challenge. In addition, attaching fluorophores may influence the way in which proteins bind to other molecules causing background signals. For these reasons, there is considerable effort to investigate alternatives for fluorescent detection. Label-free sensors detect the hybridization of an affinity complex using a variety of methods including optical, mechanical, and electrochemical techniques. Figure 1 shows a cartoon of molecules adsorbing on the surface of a silicon nanowire, which is typically much smaller than 100 nm in diameter.

In this project we are exploring the sensing limitations of silicon nanowires (Si-NWs) to electrochemically detect probe-target binding based on surface charge modulation, hence label-free detection. Si-NW sensors can be considered as nanoscale versions of the ion-sensitive field effect transistor (ISFET) sensors, invented by prof. dr. ir. Piet Bergveld in 1969, the previous chair holder of the BIOS group. The Si-NWs have been reported as capable of providing a highly sensitive label-free biomolecular sensor that can be manufactured into dense arrays and additionally provide a real-time electrical output that easily integrated with conventional data recording equipment. However, the majority of these reports fail to carefully study the sensing limitations, critical device characteristics and interface behavior.

Interested?

If you are interested and for instance would like to do your graduation work or practical term, please contact via the email address below.

Contact information

Songyue Chen & Dr. Edwin Carlen

BIOS Lab on a Chip Group

MESA+ Institute for Nanotechnology

University of Twente

P.O. Box 217

7500 AE Enschede

The Netherlands

Phone: +31 (0)53 489 2661

Fax: +31 (0)53 489 3595

E-mail: s.chen@ewi.utwente.nl & e.t.carlen@ewi.utwente.nl

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Home News & Highlights People Vacancies Research Education & Assignments Publications Intranet Internal Links External links Movies Sitemap Search	General information on Education and Assignments \| Open IOO (B3)-assignments \| Courses \| Open Masterprojects Silicon nanowire electrochemical sensors *Introduction* Lab-on-a-chip (LOC) microsystems for the detection of biomolecules at very low concentrations are becoming increasingly important for applications requiring high-throughput biomolecular analyses, such as protein arrays for basic molecular biology research, disease marker identification, and pharmaceutical drug screening. Techniques and methods used for protein arrays are improving, however, progress has been hindered by size and detection constraints. First, conventional protein arrays require relatively large sample volumes. One strategy for overcoming this problem is to significantly decrease the size and consequently the sample volume of the protein interaction assay, an ideal application of LOC. Secondly, the detection of protein and chemical pathogens (targets) is currently most commonly done using fluorescence detection of the probe-target binding. Although very sensitive, fluorescence detection suffers from the need to label the molecular target, which can lead to alterations in target-receptor interactions caused by conformational changes or steric hindrance induced by the label. The efficiency of labeling varies from protein to protein, making comparisons a challenge. In addition, attaching fluorophores may influence the way in which proteins bind to other molecules causing background signals. For these reasons, there is considerable effort to investigate alternatives for fluorescent detection. Label-free sensors detect the hybridization of an affinity complex using a variety of methods including optical, mechanical, and electrochemical techniques. Figure 1 shows a cartoon of molecules adsorbing on the surface of a silicon nanowire, which is typically much smaller than 100 nm in diameter. In this project we are exploring the sensing limitations of silicon nanowires (Si-NWs) to electrochemically detect probe-target binding based on surface charge modulation, hence label-free detection. Si-NW sensors can be considered as nanoscale versions of the ion-sensitive field effect transistor (ISFET) sensors, invented by prof. dr. ir. Piet Bergveld in 1969, the previous chair holder of the BIOS group. The Si-NWs have been reported as capable of providing a highly sensitive label-free biomolecular sensor that can be manufactured into dense arrays and additionally provide a real-time electrical output that easily integrated with conventional data recording equipment. However, the majority of these reports fail to carefully study the sensing limitations, critical device characteristics and interface behavior. *Interested?* If you are interested and for instance would like to do your graduation work or practical term, please contact via the email address below. *Contact information* Songyue Chen & Dr. Edwin Carlen BIOS Lab on a Chip Group MESA+ Institute for Nanotechnology University of Twente P.O. Box 217 7500 AE Enschede The Netherlands Phone: +31 (0)53 489 2661 Fax: +31 (0)53 489 3595 E-mail: s.chen@ewi.utwente.nl & e.t.carlen@ewi.utwente.nl