Fabrication and evaluation of micro-structured reaction field with vertically aligned carbon nanotubes for micro bio-analysis device

Abstract

For high sensitivity in micro bio-analysis devices (MBD), the fabrication of the micro-structured reaction field using vertically aligned carbon nanotubes (VACNTs) which is pillar-structured by two methods was performed. The first method is the combination of photolithography and thermal chemical vapor deposition (CVD). The second method is the molding process of polydimethylsiloxane (PDMS) substrate with micro-pillars array and the transfer press of VACNTs synthesized by thermal CVD on PDMS substrate for lower cost in mass production compared with photolithography process. In the first method, circular-pattered metal film on silicon (Si) substrate as the catalyst for VACNTs synthesis was fabricated by photolithography and VACNTs-pillars array was successfully fabricated using the substrate with circular-pattered metal film by thermal CVD. Furthermore, the protein adsorption property of these structures was evaluated as the reaction field of MBD by ultraviolet (UV) spectroscopy. The results show that the protein adsorption property was improved considering the design of micro pattern in VACNTs structures. On the other hand, in the second method, pillar-structured PDMS substrate was molded using a photoresist mold by photolithography and VACNTs was transferred on PDMS substrate by transfer-press equipment. The results indicate that VACNTs can be transferred on the top of micro pillar of PDMS substrate controlling the load of transfer press. Furthermore, it is indicated that micro-pillar VACNTs structures can be fabricated by molding and transfer press with lower cost than the combination of photolithography and thermal CVD.

The Optimization of Vertically Aligned Carbon Nanotubes’ Synthesis According to the Selected Parameters

“…In order to contribute to the increased knowledge in the field, we have focused our considerations strictly on the effect of 9 different regimes, 3 annealing times and 3 synthesis times, and its influence on the length and quality of the VACNTs. The presented research was conducted in the frame of the project focused on high sensitivity micro bio-analysis devices fabricated as the micro-structured reaction field using vertically aligned carbon nanotubes [7,8,9].…”

Influence of structural dimensions of micro-pillar array in reaction field on sensitivity of enzyme-linked immunosorbent assay (ELISA)

“…However, it has multiple steps which induce high cost for mass production. On the other hand, the bottom-up process easily builds up the form with nanometer scale from nanocomponents (for example, atom, molecular and nanomaterials) by self-assembly, but it is difficult to control the desired shape and size [13,14]. Therefore, the novel fabrication technique of MBDs is required for high quality and mass production at a low cost.…”

Rapid ELISA Using a Film-Stack Reaction Field with Micropillar Arrays

“…Miniaturizing the biomolecule- incubation region in MBDs, called the reaction field, results in a short diffusion distance of biomolecules and a high specific surface area, which is the ratio of surface area to volume. Many researchers have developed microstructured reaction fields in MBDs to increase the surface area of a reaction field for high detection sensitivity and to limit the diffusion distance of biomolecules for a rapid reaction [ 11 , 12 , 13 ]. On the other hand, the amount of biomolecules adsorbed on the surface of a reaction field is reduced due to the low sample volume used in MBDs, resulting in low detection sensitivity [ 14 , 15 ].…”

“…Moreover, ELISAs are also performed by reaction fields such as microchannels in two-dimensional microfluidics chips [ 5 , 6 ]. However, the surface area of the reaction field is small and the increase of the surface area is limited by adding microstructures such as microbeads [ 12 ] and nanomaterials with high aspect ratio [ 13 ] to a reaction field. Hence, the two-dimensional reaction field is not enough to achieve high detection sensitivity with a rapid reaction and both a higher volumetric flow rate and a higher specific surface area with a small diffusion distance are necessary for the simultaneous pursuit of high detection sensitivity and rapid reaction in MBDs.…”