Nanotechnology

Magnetic field assisted micro contact printing: a new concept of fully automated and calibrated process

Abstract

Micro contact printing (μ-CP) is a well-known and easy-to-use technology which is well established worldwide. This technology opens new opportunities for various applications. Though there is a wide range of applications, there is no standardized or calibrated system to easily reproduce micro contact printing results or to transfer scientific research to industrial applications. One of the critical points affecting the quality of μCP is being able to control the force applied on the stamp during the printing step. Up until this point, existing technologies have been based on a mechanical force. However, the drawback to this system is that stamp geometry has to be adapted to the mechanical system. In this work, we propose a new concept of magnetic field assisted micro contact printing. We report theoretical and experimental studies of the homogeneity of the force applied and the resulting deposit. Theoretical models allow the prediction of a trend between the thickness of the magnetic stamp, the iron powder concentration and the pressure applied. The versatility of this concept is proven thanks to the development of an automated prototype, the INNOSTAMP40.

Link

Magnetic field assisted micro contact printing: a new concept of fully automated and calibrated process

Dynamic PDMS inking for DNA patterning by soft lithography

Abstract

Microcontact printing (μCP) is used as a patterning technique to produce simple, rapid and cost-effective DNA microarrays. The accuracy of the final transferred pattern drastically depends on the inking step. The usual way to ink a PDMS stamp by droplet deposition of labeled biomolecules using a pipette, results in irregular transfer of the biomolecules on the chip surface and leads to poor and irreproducible fluorescent signals. These drawbacks are likely due to irregular ‘coating’ of the biomolecules on the PDMS stamp. In this work, a novel approach for inking PDMS with DNA molecules is presented. It is based on the continuous displacement of the meniscus formed by the inking solution over the surface of the stamp. When compared with the conventional technique, this dynamic PDMS inking method proved to be very reproducible for producing regular prints/spots on a functionalized glass slide, and this method could be easily extrapolated at an industrial scale.

Link

Dynamic PDMS inking for DNA patterning by soft lithography

Laser Printing of Nanoparticle Toner Enables Digital Control of Micropatterned Carbon Nanotube Growth

Abstract

Commercialization of materials utilizing patterned carbon nanotube (CNT) forests, such as hierarchical composite structures, dry adhesives, and contact probe arrays, will require catalyst patterning techniques that do not rely on cleanroom photolithography. We demonstrate the large scale patterning of CNT growth catalyst via adaptation of a laser-based electrostatic printing process that uses magnetic ink character recognition (MICR) toner. The MICR toner contains iron oxide nanoparticles that serve as the catalyst for CNT growth, which are printed onto a flexible polymer (polyimide) and then transferred to a rigid substrate (silicon or alumina) under heat and mechanical pressure. Then, the substrate is processed for CNT growth under an atmospheric pressure chemical vapor deposition (CVD) recipe. This process enables digital control of patterned CNT growth via the laser intensity, which controls the CNT density; and via the grayscale level, which controls the pixelation of the image into arrays of micropillars. Moreover, virtually any pattern can be designed using standard software (e.g., MS Word, AutoCAD, etc.) and printed on demand. Using a standard office printer, we realize isolated CNT microstructures as small as 140 μm and isolated catalyst ″pixels″ as small as 70 μm (one grayscale dot) and determine that individual toner microparticles result in features of approximately 5–10 μm . We demonstrate that grayscale CNT patterns can function as dry adhesives and that large-area catalyst patterns can be printed directly onto metal foils or transferred to ceramic plates. Laser printing therefore shows promise to enable high-speed micropatterning of nanoparticle-containing thin films under ambient conditions, possibly for a wide variety of nanostructures by engineering of toners containing nanoparticles of desired composition, size, and shape.

Link

Laser Printing of Nanoparticle Toner Enables Digital Control of Micropatterned Carbon Nanotube Growth

Page 1 of 18