A pH sensor based on electric properties of nanotubes on a glass substrate

Takeda, Seiji; Nakamura, Motonori; Ishii, Atsushi; Subagyo, Agus; Hosoi, Hirotaka; Sueoka, Kazuhisa; Mukasa, K.

doi:10.1007/s11671-007-9053-9

Cited by 30 publications

(20 citation statements)

References 16 publications

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“…Hydrogen (H + ) as a proton is able to bind to the surface of the SWNT and accept one electron from the p-orbital of the nanotube. This induces the generation of a positive hole in the SWNT and increases its conductance [11]. At the same time, the hydroxide (OH − ) ions cause the opposite effects, decreasing the conductance of the SWNT.…”

Section: Ph Sensitivitymentioning

confidence: 99%

“…Among various applications, sensor research has been one of the most widely studied topics for SWNT-based devices. An immense variety of sensors have been developed such as flow sensors [1,2], strain sensors [3,4], chemical sensors [5], gas sensors [6][7][8][9] and pH sensors [10][11][12][13]. The inherent properties of SWNTs such as small dimensions and high conductivity make them promising candidates for sensing applications.…”

Section: Introductionmentioning

confidence: 99%

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Dielectrophoresis Aligned Single-Walled Carbon Nanotubes as pH Sensors

Martin

Yeung

et al. 2011

Biosensors

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Abstract: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 patternsfabricated 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. OPEN ACCESSBiosensors 2011, 1 24

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Section: Ph Sensitivitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dielectrophoresis Aligned Single-Walled Carbon Nanotubes as pH Sensors

Martin

Yeung

et al. 2011

Biosensors

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“…Single-Walled Carbon Nanotubes (SWNTs) are promising one-dimensional nanostructured materials for electronic and sensing applications due to their unique electrical and structural properties [1,2]. Difficulty in controlling the dimensions and the properties of individual nanotubes has been a very challenging task limiting widespread applications of carbon nanotubes (CNT).…”

Section: Introductionmentioning

confidence: 99%

Patterning high density SWNT networks on flexible Parylene-C substrate

Chen¹,

Yang²,

Xiong³

et al. 2009

TRANSDUCERS 2009 - 2009 International Solid-State Sensors, Actuators and Microsystems Conference

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In this work, a directed assembly technique for controlled micro-patterning of Single-Walled Carbon Nanotubes (SWNTs) on to a flexible Parylene-C substrate has been demonstrated. A simple site-selective fluidic assembly of SWNTs has been utilized to directly assemble SWNTs on a plasma treated parylene-C substrate to form ordered high density carbon nanotube networks. Continuous nanotube micro-arrays and networks as small as 4µm wide and lengths as long as 1500µm have been fabricated.After fabrication, the parylene substrate containing the SWNT networks was peeled off from the Polycarbonate substrate. We next performed both electrical and mechanical tests to further characterize the flexible SWNT networks. The measured resistance of patterned SWNT networks was around 300Ω utilizing Au electrode pads. The test sample handled multiple bending cycles (tested up to 5 times) without showing any signs of hysteresis. High density patterning of carbon nanotube networks on flexible Parylene-C substrates has potential applications including wearable electronics and sensors, flexible field effect transistors (FETs) and interconnects.

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“…Many high-sensitivity sensors in a submicrometer scale have been investigated, such as CNT-FET and CNT modified electrodes. However, these devices are fabricated on a substrate such as a silicon substrate or glass substrate [1][2][3][4][5][6][7][8]. The device shape is strongly restricted by fabrication processes such as photolithography and electron beam lithography.…”

Section: Introductionmentioning

confidence: 99%