Novel microcantilevers withnanochannels fabricated from anodicaluminum oxide (AAO) are described. Cantilevers based on AAO canprecisely control the dimensions ofthe nanochannels and provide surface areas several orders of magnitudelarger than conventional siliconcantilevers with flat surfaces.
AAO template technology was combined with silicon technology to be directly applied to
electronic device fabrication. Thin film anodic aluminium oxide (AAO) templates were
fabricated on a silicon wafer by multiple anodizations. No electropolishing was used after
the deposition of the aluminium layer on Si wafers. The ordering of the pore arrangement
was improved by repeated anodizations, and highly ordered AAO templates could be
obtained on Si wafers.
CNT field emitter arrays were made with the AAO templates on Si wafers. Field emission
measurement revealed that the emission current density increased with the synthesis
temperature of CNTs. The large field enhancement factor in the range of 2440–4000
indicates the potential of the CNT field emitter array based on the AAO template on a Si
wafer.
Power
plants consume a major fraction of water to generate electricity,
typically in the range between 30–50% of all fresh water sources.
Most of the water from plants are lost with heat through stack and
cooling towers. It has been reported that if 20% of this water can
be recycled, power plants can be self-sustainable, allowing them to
be located with higher flexibility. Membrane contactor process can
be an effective solution to harness this source of water, but most
of the studies have been focused on dense vapor separation membranes
with limited success. In this work, we investigated a potential application
of membrane condenser technology to harness fresh water from power
plants. It has been shown that the membrane condenser configuration
can be 3 orders of magnitude more effective in recovering water compared
to dense vapor separation membranes, with a reasonable water/SO
x
selectivity of 100. We have prepared suitable
ceramic membranes as a proof-of-concept and achieved up to 85% dehumidification
efficiency in a single-pass flow. A thorough energy balance indicates
that both heat and water flux must be carefully balanced to maximize
the membrane condenser performance, and an effective module design
must be developed.
Master molds with nano-pillar structures were fabricated by using anodic aluminum oxide (AAO) for nano-imprint lithography (NIL). The proposed method consists of (1) AAO fabrication, (2) transfer of the thin AAO layer onto a substrate, (3) aluminum sputtering, (4) aluminum melting, and (5) removal of the thin AAO layer. Since the sputtered aluminum penetrated into the porous alumina walls of the AAO template during the melting step, the pillars had skin layers of aluminum/alumina composite which added additional mechanical strength and chemical resistance. The diameter of a pillar in the nano-pillar master mold was larger than that of the hole diameter of the original AAO template because of the hard skin of aluminum/alumina composite layer which covers the pillar surface. The pillar structure could be used as a mold for NIL, resulting in a regular pore array on a polymer film.
Mechanical properties of nanohoneycomb structures are measured for varying porosity (or pore diameter) of the nanohoneycomb structure. The indentation modulus and hardness in the pore direction (or thickness direction) are obtained from indentation tests using a nano-indenter. The bending modulus of the nanohoneycomb structures in the vertical direction relative to the pore (generally along the beam length) is determined from bending tests in AFM. To determine the bending modulus of the nanohoneycomb structures, the area moment of inertia of the nanohoneycomb structure is determined according to the arrangement of the pores. The indentation moduli and the hardness are found to decrease nonlinearly with increasing porosity. The bending moduli of the nanohoneycomb structures also decrease nonlinearly as a function of porosity over a large range. It is made clear that the elastic modulus of a homogenous material can be controlled by changing the pore diameter.
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