Printed Carbon Nanotube Films Research Articles

Disposable Multiwalled Carbon Nanotube Printed Film Electrochemical Determination of Acetaminophen, Dopamine, and Uric Acid

A novel printed film consisting of multiwalled carbon nanotubes was fabricated on a polyethylene terephthalate substrate by means of a mass flexographic printing process. Potential applications of this film for electrochemical biosensing were examined through the oxidation of acetaminophen, dopamine, and uric acid in phosphate buffer (pH 7.0). The results demonstrate that the printed carbon nanotube film exhibits an enhanced electrochemical response toward these molecules. Dopamine and uric acid did not interfere with each other and, thus, their simultaneous determination may be performed. The results suggest the mass flexographic printing technique has potential application for the construction of low-cost, precise, and disposable multiwalled carbon nanotube films.

Influence of surface chemistry on inkjet printed carbon nanotube films

Carbon nanotube ink chemistry and the proper formulation are crucial for direct-write printing of nanotubes. Moreover, the correct surface chemistry of the self-assembled monolayers that assist the direct deposition of carbon nanotubes onto the substrate is equally important to preserve orientation of the printed carbon nanotubes. We report that the successful formulation of two single walled carbon nanotube (SWNT) inks yields a consistent, homogenous printing pattern possessing the requisite viscosities needed for flow through the microcapillary nozzles of the inkjet printer with fairly modest drying times. The addition of an aqueous sodium silicate allows for a reliable method for forming a uniform carbon nanotube network deposited directly onto unfunctionalized surfaces such as glass or quartz via inkjet deposition. Furthermore, this sodium silicate ingredient helps preserve applied orientation to the printed SWNT solution. Sheet resistivity of this carbon nanotube ink formula printed on quartz decreases as a function of passes and is independent of the substrate. SWNTs were successfully patterned on Au. This amine-based surface chemistry dramatically helps improve the isolation stabilization of the printed SWNTs as seen in the atomic force microscopy (AFM) image. Lastly, using our optimized SWNT ink formula and waveform parameters in the Fuji materials printer, we are able to directly write/print SWNTs into 2D patterns. Dried ink pattern expose and help orient roped carbon nanotubes that are suspended in ordered arrays across the cracks.

The patterned electron field emission of printed carbon nanotube films by image transfer technology

The patterned electron field emission of printed carbon nanotube (PCNT) films using image transfer technology is reported. If we transfer an image to the surface of PCNT films, such as using a stamp, the emission image of PCNT films will be the transferred pattern. Based on many experiments, we are convinced that the essential feature of pattern emission from PCNT films by image transfer technology is the great emission enhancement of the image transferred area and the reduced emission from the raw area. According to the results from field emission scanning electron microcopy (FESEM), we suggest that the connecting CNT bundles protruding from the substrate result in the emission enhancement of the image transferred area. At the same time, the emission current increase causes the external and internal voltage drop to increase which results in a decrease in the emission from the untreated area. Using image transfer technology, a well-resolved emission image of PCNT films could easily be obtained without any post-treatment.

The influence of organophilic clay on field electron emission uniformity and lifetime of screen printed carbon nanotube film

The effect of adding clay, modified by a silane coupling agent, into the carbon nanotube (CNT) paste on the field electron emission and a lifetime of screen printed CNT film was studied. The composition of organophilic clay and CNTs was characterized by a combination of X-ray diffraction, and scanning electron microscopy. The incorporation of clay improved the dispersivity, adhesiveness, and conductive networking of paste, therewith enhancing the field emission's uniformity and stability. The improvement of this gas barrier on the CNT film by clay loading prevents emission degradation.

Turn-on field distribution of field-emitting sites in carbon nanotube film: Study with luminescent image

The turn-on field distribution of emission sites in carbon nanotube (CNT) film are measured by counting lighting dots. This provides a convenient method to characterize the field-emission uniformity of a CNT cathode. With this method, a quantitative characterization of the emission-uniformity improvement of a printed CNT film after a conditioning is obtained. The turn-on field distribution of an array of CNT dots in a pixel also can be measured with this method.

Electron translocation and field emission in printed CNT film by high-temperature sintering and post-treatment

The main problem of printed carbon nanotube film (CNTF) is that emitters do not have distributed uniformity. CNT was buried in leftover binding materials, which needs to be removed by fitted sintering and post-treatment. A new paste for printed CNTF was developed. Tunneling coefficients of leftover potential barrier were calculated respectively by the numerical method. The electrons translocation results through potential barrier between CNTs in calculated CNTF were tested by an experiment. A novel post-treatment, including high-temperature sintering and mechanical shearing and blowing, was performed to evidently improve the electron translocation and field emission current density of CNTF. Excellent emission prosperities were exhibited: stable current density, distributed uniformity emitters and long lifetime. The treatment of high-temperature sintering and mechanical shearing and blowing, may be an important prerequisite for future field emission display.

Comparison on Different Post-treatment Methods of Printed Carbon Nanotube Films for Enhanced Field Emission

Four kinds of different post-treatment methods or conditions, including low residue adhesive tape treatment, high residue adhesive tape treatment, plasma exposure treatment and mechanical crushing and blowing treatment, were applied to screen-printed carbon nanotube (CNT) films to improve their field emission ability. The effects and results of these methods or conditions on field emission characteristics of printed CNT films were compared in some aspects such as I-V curves, luminescent images and annealing treatment and so on.

Improvement of luminescent stability from carbon nanotube field emission display based on printed CNT film

Aiming at the influences of poor contact at carbon nanotube (CNT)/electrode interface on luminescence stability in printed CNT film, a new co-sintering process for cathode fabrication was presented to improve the luminescent stability of fully printed CNT-FED. By co-sintering the printed silver and CNT layers, CNTs geometrically matched with Ag surface and/or embedded into Ag layer at the bottom of the co-sintered film, large CNTs block and bulk silver nested each other at the top of the co-sintered film. All these structures increased the contact area at CNT/Ag interface, which could increase the probability of forming ohmic contact at CNT/Ag interface. The luminescent stability of printed CNT-FED with co-sintered cathode could be improved as 5.6 times high as that of common devices.

Improvement of Field-Emission Properties of Screen Printed Carbon Nanotube Films via Argon Plasma Treatment

In this paper, we describe an effective surface treatment to improve the field emission site density. The carbon nanotube (CNT) films fabricated by a screen printing process have been exposed to Ar plasma for varying durations and their field emission characteristics have been measured. The CNT films, after applying an Ar plasma treatment, have excellent field emission characteristics with very high emission current and low threshold fields. Scanning electron microscopy showed the contamination removal from the surface of the CNT films, and transmission electron microscopy showed the structural modification of the CNT walls after exposure to Ar plasma. Raman results showed that the particles generated by the deformation of the CNT structure had characteristics of both single-wall carbon nanotubes (SWCNTs) and multiwall carbon nanotubes (MWCNTs). We attribute improvement of field emission properties to the changes of the geometrical structure of the local emission region in MWCNTs.

A novel mechanical approach to improve the field emission characteristics of printed CNT films

A novel post-treatment method is presented to improve the field emission properties of printed carbon nanotube (CNT) films. Screen-printed multi-walled CNT (MWNT) film was treated by mechanical crushing method and cleaned by high-speed airflow. Compared to those of un-treated film, the turn-on electric field of the treated film decreased from 2.5 to 1.7 V/μm, and the total emission current of the treated film that has the same printing area as the un-treated one increased from ∼120 to ∼1000 μA. SEM study revealed that the enhanced field emission is due to the removal of residual materials covered on the surface of CNTs.

Efficient electron emissions from printed carbon nanotubes by surface treatments

The fabrication of carbon nanotube (CNT) emitters with excellent field emission properties was described. CNT clusters synthesized by arc discharge were crushed, mixed with conductive pastes, and then screen-printed. In order to obtain efficient field emissions, the mechanical surface treatment was applied to the printed CNT films. The measurements of field emission carried out using a diode structure showed that the electron emission of the surface-treated CNT films uniformly turned-on with a field as low as about 1.5 V/μm. The emission current density was about 0.6 mA/cm2 at a field of 2.8 V/μm. Furthermore, we proposed a new triode type field emitter using a mesh gate plate having tapered holes. Combining the surface-treated CNT emitters and the mesh gate plate, we could achieve the ideal triode properties with no gate leakage currents. New suggestions of mesh gate structure can be an alternative cathode technology for field emission display.