ABSTRACT Optic fluidic devices, which combine optical elements such as adaptive optical lenses or... more ABSTRACT Optic fluidic devices, which combine optical elements such as adaptive optical lenses or diffraction gratings into micro-fluidic devices, are now becoming increasingly important for environmental monitoring, medical diagnostics and chemical detection. In this paper, we present a novel and simple micro/nanofabrication process for SU-8 based optic fluidics structures with phase gratings on the bottom of the micro-channel using our silicon grating templates. The refraction index difference between the fluid and the SU-8 gratings generates a modulation in the phase of the light passing through the device. Our method of fabricating optic fluidic device is promising to be economic in fabrication, high throughput in production and have potential applications for sensing.
Polyacrylamide hydrogels were prepared with variable stiffness within a range of effective surfac... more Polyacrylamide hydrogels were prepared with variable stiffness within a range of effective surface Young's modulus values from 5.5 kPa to 152 kPa measured in the hydrated state using atomic force microscopy (AFM). The gel surface was modified with either collagen or ...
ABSTRACT In this work, we demonstrate a novel SU8/SiO2 /PMMA trilayer nanoimprint technique to fa... more ABSTRACT In this work, we demonstrate a novel SU8/SiO2 /PMMA trilayer nanoimprint technique to fabricate the silicon nanowire (SiNW) sensor used for gas detection. The SiNW sensor fabricated in our experiment is based on the silicon on insulator (SOI) substrate which is doped by boron with a dopant concentration of 8 times 1017 cm-3. Two nanowire sensors with different linewidths as well as a thin-film plane device were fabricated for comparison. The fabricated devices were then used for detecting 250 ppm NO2 and 250 ppm NH3. The results show a large enhanced sensitivity especially for the narrower device. Finally, a computer simulation work was done to qualitatively explain our experimental results.
Summary form only given. The reflex klystron is a promising candidate for use as a source of subm... more Summary form only given. The reflex klystron is a promising candidate for use as a source of submillimeter-wave power at the milliwatt level. Such sources are required to fulfill the requirements for small-footprint, cost-effective and efficient fundamental sources for medical imaging and remote sensing applications at terahertz frequencies. Dimensional constraints associated with traditional manufacturing techniques, material issues and the performance
By combining nanoimprint lithography and traditional hydrothermal growth method of ZnO nanorods, ... more By combining nanoimprint lithography and traditional hydrothermal growth method of ZnO nanorods, vertical and well patterned ZnO nanostructures were successfully fabricated. The imprinted SU-8 resist deep trenches above the ZnO seed layer prohibit the lateral growth of ZnO nanorods. Various patterned vertical ZnO nanostructures like nanorods and nanowalls can be obtained. The improvement of photoluminescence property of ZnO nanorods was observed after removing the SU-8 resist from the substrate by O2 reactive ion etching (RIE).
Journal of vacuum science and technology, Apr 25, 2011
This article reports a novel method to effectively modify the surface stiffness for the different... more This article reports a novel method to effectively modify the surface stiffness for the differentiation of stem cell growth. To achieve large range of surface hardness, focused electron beam is first employed to radiate hydrogen silsesquioxane (HSQ) film. With different degrees of curing caused by certain e-beam exposure, the HSQ demonstrates various Young’s modulus from 0.5 to 2 GPa, measured by an atomic force microscope. Fourier transform infrared spectra were used to investigate the origin of the stiffness change, which is due to the e-beam irradiation induced network formation inside HSQ. The novel technique possesses a number of advantages such as precision control of stiffness in a broad matrix with high spatial resolution. It also offers a good opportunity to define the geometry shape with a constant stiffness in nanometer scale.
ABSTRACT Parallel scanning with arrays of AFM cantilevers has an advantage over conventional sing... more ABSTRACT Parallel scanning with arrays of AFM cantilevers has an advantage over conventional single AFM probes because of increased acquisition speed for sample imaging. A challenge for such large arrays is the simultaneous detection of deflection of a multitude of cantilevers. In addition, conventional AFM probes lack flexibility in cantilever array design, and material conventionally used is not soft enough for some applications such as imaging cells for biology. In this paper, alternative arrays of polymer SU-8 microcantilevers with moulded tips and integrated piezoresistive sensors are fabricated to demonstrate parallel imaging of large sample areas. Cantilevers with a variety of SU-8 thicknesses (0.8–8.5 μm) are investigated. SU-8 cantilevers and SU-8 tips are formed at the same time by casting SU-8 into 10 μm-deep pyramidal moulds, which are created by anisotropic KOH etching. Further, photolithographic processes and metal deposition, such as lift-off and electroplating, are combined to define piezoresistive sensors on top of fabricated SU-8 cantilevers. SU-8 cantilever arrays are tested in parallel contact-mode scanning of surfaces and topography on micro/nano structures. Parallel imaging with SU-8 cantilever arrays is carried out by data acquisition and analysis of resistance changes in the integrated sensors.
ABSTRACT In this work, we demonstrate the fabrication of silicon nanowires, with their widths ran... more ABSTRACT In this work, we demonstrate the fabrication of silicon nanowires, with their widths ranging from 22nm to 110nm, using the combination of bilayer nanoimprint and angle deposition. The approach makes the widths of the nanowires adjustable, offering an alternative solution for high-resolution, low-cost, and high-throughput fabrication of nanowire sensors. Using this approach, silicon nanowires with different widths are formed on the boron-doped top Si layers of the SOI substrates, and are used as sensing parts of the gas sensors. The Si nanowire sensors with wire widths of 60nm and 90nm demonstrate relative sensitivities of 155% and 44% to the testing gas of NO2.
Some of the most important steps in manufacturing microelectromechnical systems (MEMS) are their ... more Some of the most important steps in manufacturing microelectromechnical systems (MEMS) are their assembly and handling. With handling we mean the way we can safely, without damages, pick microparts of any shape or any kind of material, rotate them to the desired orientation and finally position them precisely on or connect them with other microparts. For these purposes, specially designed tools - microgrippers - are required. This paper presents the design, development, fabrication method using the SU8 technology and post-fabrication processes with the goal to obtain a new type of micro-gripper. This micro-gripper was produced for a handling and assembly station developed at the IMFT (TU Wien). To investigate the obtained structures we performed a
ABSTRACT Optic fluidic devices, which combine optical elements such as adaptive optical lenses or... more ABSTRACT Optic fluidic devices, which combine optical elements such as adaptive optical lenses or diffraction gratings into micro-fluidic devices, are now becoming increasingly important for environmental monitoring, medical diagnostics and chemical detection. In this paper, we present a novel and simple micro/nanofabrication process for SU-8 based optic fluidics structures with phase gratings on the bottom of the micro-channel using our silicon grating templates. The refraction index difference between the fluid and the SU-8 gratings generates a modulation in the phase of the light passing through the device. Our method of fabricating optic fluidic device is promising to be economic in fabrication, high throughput in production and have potential applications for sensing.
Polyacrylamide hydrogels were prepared with variable stiffness within a range of effective surfac... more Polyacrylamide hydrogels were prepared with variable stiffness within a range of effective surface Young's modulus values from 5.5 kPa to 152 kPa measured in the hydrated state using atomic force microscopy (AFM). The gel surface was modified with either collagen or ...
ABSTRACT In this work, we demonstrate a novel SU8/SiO2 /PMMA trilayer nanoimprint technique to fa... more ABSTRACT In this work, we demonstrate a novel SU8/SiO2 /PMMA trilayer nanoimprint technique to fabricate the silicon nanowire (SiNW) sensor used for gas detection. The SiNW sensor fabricated in our experiment is based on the silicon on insulator (SOI) substrate which is doped by boron with a dopant concentration of 8 times 1017 cm-3. Two nanowire sensors with different linewidths as well as a thin-film plane device were fabricated for comparison. The fabricated devices were then used for detecting 250 ppm NO2 and 250 ppm NH3. The results show a large enhanced sensitivity especially for the narrower device. Finally, a computer simulation work was done to qualitatively explain our experimental results.
Summary form only given. The reflex klystron is a promising candidate for use as a source of subm... more Summary form only given. The reflex klystron is a promising candidate for use as a source of submillimeter-wave power at the milliwatt level. Such sources are required to fulfill the requirements for small-footprint, cost-effective and efficient fundamental sources for medical imaging and remote sensing applications at terahertz frequencies. Dimensional constraints associated with traditional manufacturing techniques, material issues and the performance
By combining nanoimprint lithography and traditional hydrothermal growth method of ZnO nanorods, ... more By combining nanoimprint lithography and traditional hydrothermal growth method of ZnO nanorods, vertical and well patterned ZnO nanostructures were successfully fabricated. The imprinted SU-8 resist deep trenches above the ZnO seed layer prohibit the lateral growth of ZnO nanorods. Various patterned vertical ZnO nanostructures like nanorods and nanowalls can be obtained. The improvement of photoluminescence property of ZnO nanorods was observed after removing the SU-8 resist from the substrate by O2 reactive ion etching (RIE).
Journal of vacuum science and technology, Apr 25, 2011
This article reports a novel method to effectively modify the surface stiffness for the different... more This article reports a novel method to effectively modify the surface stiffness for the differentiation of stem cell growth. To achieve large range of surface hardness, focused electron beam is first employed to radiate hydrogen silsesquioxane (HSQ) film. With different degrees of curing caused by certain e-beam exposure, the HSQ demonstrates various Young’s modulus from 0.5 to 2 GPa, measured by an atomic force microscope. Fourier transform infrared spectra were used to investigate the origin of the stiffness change, which is due to the e-beam irradiation induced network formation inside HSQ. The novel technique possesses a number of advantages such as precision control of stiffness in a broad matrix with high spatial resolution. It also offers a good opportunity to define the geometry shape with a constant stiffness in nanometer scale.
ABSTRACT Parallel scanning with arrays of AFM cantilevers has an advantage over conventional sing... more ABSTRACT Parallel scanning with arrays of AFM cantilevers has an advantage over conventional single AFM probes because of increased acquisition speed for sample imaging. A challenge for such large arrays is the simultaneous detection of deflection of a multitude of cantilevers. In addition, conventional AFM probes lack flexibility in cantilever array design, and material conventionally used is not soft enough for some applications such as imaging cells for biology. In this paper, alternative arrays of polymer SU-8 microcantilevers with moulded tips and integrated piezoresistive sensors are fabricated to demonstrate parallel imaging of large sample areas. Cantilevers with a variety of SU-8 thicknesses (0.8–8.5 μm) are investigated. SU-8 cantilevers and SU-8 tips are formed at the same time by casting SU-8 into 10 μm-deep pyramidal moulds, which are created by anisotropic KOH etching. Further, photolithographic processes and metal deposition, such as lift-off and electroplating, are combined to define piezoresistive sensors on top of fabricated SU-8 cantilevers. SU-8 cantilever arrays are tested in parallel contact-mode scanning of surfaces and topography on micro/nano structures. Parallel imaging with SU-8 cantilever arrays is carried out by data acquisition and analysis of resistance changes in the integrated sensors.
ABSTRACT In this work, we demonstrate the fabrication of silicon nanowires, with their widths ran... more ABSTRACT In this work, we demonstrate the fabrication of silicon nanowires, with their widths ranging from 22nm to 110nm, using the combination of bilayer nanoimprint and angle deposition. The approach makes the widths of the nanowires adjustable, offering an alternative solution for high-resolution, low-cost, and high-throughput fabrication of nanowire sensors. Using this approach, silicon nanowires with different widths are formed on the boron-doped top Si layers of the SOI substrates, and are used as sensing parts of the gas sensors. The Si nanowire sensors with wire widths of 60nm and 90nm demonstrate relative sensitivities of 155% and 44% to the testing gas of NO2.
Some of the most important steps in manufacturing microelectromechnical systems (MEMS) are their ... more Some of the most important steps in manufacturing microelectromechnical systems (MEMS) are their assembly and handling. With handling we mean the way we can safely, without damages, pick microparts of any shape or any kind of material, rotate them to the desired orientation and finally position them precisely on or connect them with other microparts. For these purposes, specially designed tools - microgrippers - are required. This paper presents the design, development, fabrication method using the SU8 technology and post-fabrication processes with the goal to obtain a new type of micro-gripper. This micro-gripper was produced for a handling and assembly station developed at the IMFT (TU Wien). To investigate the obtained structures we performed a
Uploads
Papers by Ejaz Huq