Carbon nanotube‐sensor‐integrated microfluidic platform for real‐time chemical concentration detection

Abstract

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 low, i.e. in the range of nanowatts. These results indicate great potential of EG-CNT for advanced nanosensors with superior sensitivity, ultra-low power consumption, and less fabrication complexity.

Electrical and Electrochemical Sensors Based on Carbon Nanotubes for the Monitoring of Chemicals in Water—A Review

“…Regarding free chlorine (or hypochlorite detection for detection at pH higher than 7), the non-functionalized, aligned MWCNT-based chemistor device shows the lowest LOD below 5 ppb. The sensitivity in this reference is attributed to the oxidative properties of NaOCl leading to doping effect of the CNTs [ 191 ].…”

Glass/PDMS hybrid microfluidic device integrating vertically aligned SWCNTs to ultrasensitive electrochemical determinations

“…[8][9][10][11][12][13] This platform was applied also in a capillary electrophoresis (CE) microchip. 14,15 Applications in electrophoretic systems, meanwhile, exhibit drawbacks related to interferences between the electric fields of detection and separation.…”

Technology and Applications of Microbial Biosensor

“…The biotic-micro electrochemical system developed by the integration of a microbe onto the microfluidic chip offers promising characteristics of a fast response and small size. Lab-on-a-chip technology are widely used in fabricating microfluidic devices [29], which enable the detection of analytes at ultra-low concentrations by actively transporting target analytes to the surface of the microbial biosensors [91,92]. Lab-ona-chip shows great promise for the development of microbial biosensors.…”