Wireless swnt sensor integrated with microfluidic system for various liquid sensing applications

Abstract

Sensors based on single-walled carbon nanotubes (SWNT) are integrated into a microfluidic system outfitted with data processing and wireless transmission capability. The sensors combine the sensitivity, specificity, and miniature size of SWNT-based nanosensors with the flexible fluid handling power of microfluidic “lab on a chip” analytical systems. Methods of integrating the SWNT-based sensor into a microfluidic system are compatible with the delicate nature of the SWNT sensor elements. The sensor devices are capable of continuously and autonomously monitoring and analyzing liquid samples in remote locations, and are applicable to real time water quality monitoring and monitoring of fluids in living systems and environments. The sensor devices and fabrication methods of the invention constitute a platform technology, because the devices can be designed to specifically detect a large number of distinct chemical agents based on the functionalization of the SWNT. The sensors can be combined into a multiplex format that detects desired combinations of chemical agents simultaneously.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims the priority of U.S. Provisional Application No. 61 / 584,857 filed Jan. 10, 2012 and entitled “Wireless SWNT Sensor Integrated With Microfluidic System for Various Liquid Sensing Applications”, the whole of which is hereby incorporated by reference.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT[0002]The invention was developed with financial support from Grant No. 0731102 from the National Science Foundation. The U.S. Government has certain rights in the invention.BACKGROUND[0003]Pollutants in water have significant impact on human health and the natural environment. Environmental contamination, such as high levels of nutrients, industrial wastes, toxic chemicals, and algal blooms can lead to mass mortality in fish and seabirds and may possibly result in disease outbreaks. Conventional water quality evaluation is typically conducted by on-site sampling followed by transport to a laboratory for testi...

AI Technical Summary

Benefits of technology

The present invention is a sensor device that integrates the sensitivity, specificity, and miniature size of SWNT-based sensors with the flexible fluid handling power of microfluidic "lab on a chip" analytical systems. The device can detect and analyze chemical agents in liquid samples, particularly in remote or poorly accessible locations. It is directly applicable to water quality monitoring and bioanalytical monitoring in living systems. The device includes a substrate, a patterned conductive layer, a microelectrodes gap, and a nanosensor that spans the gap and is enclosed by a microfluidic channel. The microelectrodes apply an AC voltage to assemble the nanosensor, and the assembled nanosensor detects the chemical agent through its electrical properties. The sensor device can be fabricated using microfluidic techniques and is compatible with delicate sensor elements. The method of fabricating the sensor device involves depositing a conductive layer onto a substrate, flowing an aqueous suspension of SWNT through a microfluidic channel, applying an AC voltage, and removing the aqueous suspension. The sensor device can detect or quantify the chemical agent in a liquid sample by observing an output signal from the detection circuit.

Problems solved by technology

Environmental contamination, such as high levels of nutrients, industrial wastes, toxic chemicals, and algal blooms can lead to mass mortality in fish and seabirds and may possibly result in disease outbreaks.

Such procedures are costly, time consuming, and require skilled operators.

Further, the test results can only indicate the quality of water at the specific time and location of sampling.

However, such a plasma treatment of a carbon nanotube-based device would damage the nanotubes.

However, this type of integration process could introduce contamination onto the SWNT from the etching solution and the substances generated by the chemical reactions.

Bourlon and colleagues have fabricated a flow and ionic sensor using a nanotube transistor covered with a PDMS channel without using an oxygen plasma treatment [13]; however, the microfluidic channel was not well sealed on the device which resulted in leakage of solution.

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