The simultaneous operation of near-field scanning optical microscopy (NSOM) in reflection and transmission modes is demonstrated. In the transmission mode, a low-noise, large-area silicon photodetector was mounted between the piezoelectric transducer scanning stage and the sample. In the reflection mode, either a photomultiplier tube or two large-area silicon detectors was used for signal collection. The reflection-mode setup consisting of two silicon detectors provides a large numerical aperture of 0.9 as well as symmetrical detection of emitting photons. The dielectric thin films and the light-emitting polymers were used to demonstrate the capability of these two modes of NSOM. A comparison between these two different setups is also presented.

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Large-area and uniformly distributed 3-aminopropyltriethoxysilane (γ-APTES) incorporated with poly-dimethylsiloxane-treated hydrophobic fumed silica nanoparticles (NPs) sensing membranes with different mixed ratios were deposited by using ultrasonic liquid atomizer (ULA) spray. Nanoscale current–voltage (I–V) characteristics of the deposited membranes were then characterized by using conductive atomic force microscopy. It is found that the ULA-sprayed γ-APTES plus NPs (γ-APTES + NPs) membrane has smaller leakage current and higher breakdown voltage than does the ULA-sprayed pure γ-APTES membrane. Excellent glucose sensing performances are found when using the deposited ULA-sprayed γ-APTES + NPs as sensing membrane on polysilicon wire sensor. Further sensing performance enhancement was obtained as the γ-APTES + NPs membrane was subjected to UV illumination. Our experiment’s results confirmed that the ULA spray is a promising method for large area deposition of γ-APTES + NPs membrane and that it can be utilized for biomedical sensor applications.

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