Integration of nanosensors into a sealed microchannel in a hybrid lab-on-a-chip device (original) (raw)
Commonly used assembly methods for microfluidic devices rely heavily on direct, manual bonding of different components with limited visual aids. The manual operation is likely to cause damage to existing structures, especially to nanoscale sensors on the substrate. Here we report a novel approach to integrate nanosensors into a lab-on-a-chip device with total elimination of operational errors from the manual bonding process. The microfluidic components are composed of an ultraviolet (UV) light-defined, cross-linked SU-8 microchannel and a polydimethylsiloxane (PDMS) top cover. The hybrid microfluidic structure provides a fully sealed microchannel and precisely positioned features. Well-organized single-walled carbon nanotube (SWNT) thin films are deposited and aligned across the electrodes on a silicon substrate with dielectrophoresis. The assembly of SWNTs is carried out in a sealed microchannel which eliminates the potential damage of the nanosensors during the bonding process. The SWNT devices are configured as two-terminal resistor-type sensors with the metal electrodes as the probing pads and the dielectrophoretically captured SWNTs as the sensing elements. To demonstrate the feasibility of this integration approach, an assembled SWNT device is measured as an integrated flow sensor to monitor the flow rate in the microchannel. This lab-on-a-chip device is designed as a platform that can be expanded for more applications. For example, with minimal modifications, the device can be used in chemical sensing, biosensing, and medical research.
Related papers
ELECTROPHORESIS, 2009
This paper presents the development of a chemical sensor employing electronic‐grade carbon nanotubes (EG‐CNTs) as the active sensing element for sodium hypochlorite detection. The sensor, integrated in a PDMS‐glass microfluidic chamber, was fabricated by bulk aligning of EG‐CNTs between gold microelectrode pairs using dielectrophoretic technique. Upon exposure to sodium hypochlorite solution, the characteristics of the carbon nanotube chemical sensor were investigated at room temperature under constant current mode. The sensor exhibited responsivity, which fits a linear logarithmic dependence on concentration in the range of 1/32 to 8 ppm, a detection limit lower than 5 ppb, while saturating at 16 ppm. The typical response time of the sensor at room temperature is on the order of minutes and the recovery time is a few hours. In particular, the sensor showed an obvious sensitivity to the volume of detected solution. It was found that the activation power of the sensor was extremely l...
Nanotubes/nanowires-based, microfluidic-integrated transistors for detecting biomolecules
Microfluidics and Nanofluidics, 2010
Nanotubes and nanowires have sparked considerable interest in biosensing applications due to their exceptional charge transport properties and size compatibility with biomolecules. Among the various biosensing methodologies incorporating these nanostructured materials in their sensing platforms, liquid-gated field-effect transistors (LGFETs)-based device configurations outperform the conventional electrochemical measurements by their ability in providing label free, direct electronic read-out, and real-time detection. Together with integration of a microfluidic channel into the device architecture, nanotube- or nanowires-based LGFET biosensor have demonstrated promising potential toward the realization of truly field-deployable self-contained lab-on-chip devices, which aim to complement the existing lab-based methodologies. This review addresses the recent advances in microfluidic-integrated carbon nanotubes and inorganic nanowires-based LGFET biosensors inclusive of nanomaterials growth, device fabrication, sensing mechanisms, and interaction of biomolecules with nanotubes and nanowires. Design considerations, factors affecting sensing performance and sensitivity, amplification and multiplexing strategies are also detailed to provide a comprehensive understanding of present biosensors and future sensor systems development.
Loading Preview
Sorry, preview is currently unavailable. You can download the paper by clicking the button above.