Jing-Jenn Lin

Polysilicon wire glucose sensor highly immune to interference

This study investigated the interference elimination ability of a glucose sensor made of polysilicon wire (PSW) with a surface modified by 3-aminopropyltriethoxysilane mixed with polydimethylsiloxane-treated hydrophobic fumed silica nanoparticles plus ultra-violet illumination (γ-APTES+NPs+UV). Glucose sensing of the PSW sensor in the presence of five common interferences such as ascorbic acid (AA), uric acid (UA), acetaminophen (AP), L-cysteine (Lys), and citric acid (CA) was performed. We found that the disturbance caused by the interferences was low for interference-to-glucose concentration ratios up to 600:1 if the PSW surface is modified with γ-APTES+NPs+UV. The outstanding interference immunity of this PSW glucose sensor is believed to be mainly due to the fact that it is a dry-type sensor and the extremely low leakage of the γ-APTES+NPs membrane which allows the PSW to show three orders of magnitude lower leakage current than with the γ-APTES membrane only. In addition to its excellent interference immunity, the PSW glucose sensor with a line width of 100 nm also exhibits a wide linear detection range, an ultra-high sensitivity, an ultra low detection limit, and it can be reused more than a thousand times without much sensitivity degradation.

Characteristics of Polysilicon Wire Glucose Sensors with a Surface Modified by Silica Nanoparticles/γ-APTES Nanocomposite

This report investigates the sensing characteristics of polysilicon wire (PSW) glucose biosensors, including thickness characteristics and line-width effects on detection limits, linear range and interference immunity with membranes coated by micropipette/spin-coating and focus-ion-beam (FIB) processed capillary atomic-force-microscopy (C-AFM) tip scan/coating methods. The PSW surface was modified with a mixture of 3-aminopropyl-triethoxysilane (γ-APTES) and polydimethylsiloxane (PDMS)-treated hydrophobic fumed silica nanoparticles (NPs). We found that the thickness of the γ-APTES+NPs nonocomposite could be controlled well at about 22 nm with small relative standard deviation (RSD) with repeated C-AFM tip scan/coatings. The detection limit increased and linear range decreased with the line width of the PSW through the tip-coating process. Interestingly, the interference immunity ability improves as the line width increases. For a 500 nm-wide PSW, the percentage changes of the channel current density changes (ΔJ) caused by acetaminophen (AP) can be kept below 3.5% at an ultra-high AP-to-glucose concentration ratio of 600:1. Simulation results showed that the line width dependence of interference immunity was strongly correlated with the channel electrical field of the PSW biosensor.

Detecting the effect of targeted anti-cancer medicines on single cancer cells using a poly-silicon wire ion sensor integrated with a confined sensitive window

A mold-cast polydimethylsiloxane (PDMS) confined window was integrated with a poly-silicon wire (PSW) ion sensor. The PSW sensor surface inside the confined window was coated with a 3-aminopropyltriethoxysilane (γ-APTES) sensitive layer which allowed a single living cell to be cultivated. The change in the microenvironment due to the extracellular acidification of the single cell could then be determined by measuring the current flowing through the PSW channel. Based on this, the PSW sensor integrated with a confined sensitive window was used to detect the apoptosis as well as the effect of anti-cancer medicines on the single living non-small-lung-cancer (NSLC) cells including lung adenocarcinoma cancer cells A549 and H1299, and lung squamous-cell carcinoma CH27 cultivated inside the confined window. Single human normal cells including lung fibroblast cells WI38, lung fibroblast cells MRC5, and bronchial epithelium cell Beas-2B were tested for comparison. Two targeted anti-NSCLC cancer medicines, Iressa and Staurosporine, were used in the present study. It was found that the PSW sensor can be used to accurately detect the apoptosis of single cancer cells after the anti-cancer medicines were added. It was also found that Staurosporine is more effective than Iressa in activating the apoptosis of cancer cells.

Effects of Targeted Anticancer Medicines on Post-Cell Removal SurfaceMorphology of Cancer Cells Cultivated on 3-AminopropyltriethoxysilaneSurface

A post-cell-removal surface morphology (PCRSM) profiling technique was used to identify the effects of targeted anticancer medicines on cancer cells. Living non-small lung cancer cells, A549 and H1299, were cultivated on a 3-aminopropyltriethoxysilane (γ-APTES) coated silicon wafer surface with and without targeted anticancer medicine added in the culture medium. Atomic force microscopy (AFM) was used to examine the surface morphology profile on the γ-APTES wafer surface after removing the cells. Two different targeted anticancer medicines, epidermal growth factor receptor (EGFR)-inhibitor Iressa (gefitinib) and protein kinase c (PKC)-inhibitor Staurosporine were examined. Our experimental results show that only the cancer cells treated with Staurosporine can have the PCRSM profiles resemble to those of normal cells, whereas those treated with Iressa reserve the PCRSM profiles of the pre-medicine treated cancer cells. This observation indicates that the PCRSM technique is able to detect the cell-traction force difference caused by EGFR-inhibitor and PKC-inhibitor, respectively and Staurosporine is more effective than Iressa in deactivating the cell-substrate interaction of the cancer cells.

Electrical characterization of single cells using polysilicon wire ion sensor in an isolation window

A polysilicon wire (PSW) sensor can detect the H+ ion density (pH value) of the medium coated on its surface, and different cells produce different extracellular acidification and hence different H+ ion densities. Based on this, we used a PSW sensor in combination with a mold-cast polydimethylsiloxane (PDMS) isolation window to detect the adhesion, apoptosis and extracellular acidification of single normal cells and single cancer cells. Single living human normal cells WI38, MRC5, and BEAS-2B as well as non-small-cell lung cancer (NSCLC) cells A549, H1299, and CH27 were cultivated separately inside the isolation window. The current flowing through the PSW channel was measured. From the PSW channel current change as a function of time, we determined the cell adhesion time by observing the time required for the current change to saturate, since a stable extracellular ion density was established after the cells were completely adhered to the PSW surface. The apoptosis of cells can also be determined when the channel current change drops to zero. We found that all the NSCLC cells had a higher channel current change and hence a lower pH value than the normal cells anytime after they were seeded. The corresponding average pH values were 5.86 for A549, 6.00 for H1299, 6.20 for CH27, 6.90 for BEAS-2B, 6.96for MRC5, and 7.02 for WI38, respectively, after the cells were completely adhered to the PSW surface. Our results show that NSCLC cells have a stronger cell-substrate adhesion and a higher extracellular acidification rate than normal cells.

Comparison of multiple-polysilicon-nanowire pH-sensors coated with different ALD-deposited high-k dielectric materials

Multiple poly-silicon nanowires (PS-NWs) coated with different high-k dielectric materials, HfO2, Al2O3, and TiO2, were fabricated and their pH sensing characteristics were compared. Sidewall spacer formation technique was used for the PS-NWs fabrication and all the high-k materials were deposited by atomic-layer-deposition (ALD). Following the high-k dielectric deposition, a 3-aminopropyltriethoxysilane (y-APTES) layer was coated as sensing membrane. It is found that the multiple PS-NW sensor coated with HfO2 exhibits the highest sensitivity and best reproducibility for pH sensing.

Improvement of Radiation-Induced Degradation in MOSFET by Using Glass Fiber/Epoxy/Silica Nanoparticles/γ-APTES Composite as Shielding Materials for High-Energy Radiation

Our recent study showed that the trapping charges of the polysilicon wire sensor caused by γ-ray radiation primarily concentrated in the γ-APTES/silica nanoparticles composite layer covered on the sensor. In this chapter, we investigate the shielding effect of the glass fiber/epoxy/silica nanoparticles/γ-APTES composite materials for high-energy radiation in commercially available MOSFET. The use of glass fiber/epoxy/silica nanoparticles/γ-APTES composite plate shielding during irradiation improved the post-irradiated degradation of transfer characteristics by three orders of magnitude for the pMOSFET and half an order of magnitude for the nMOSFET, respectively, as compared to the pMOSFET and nMOSFET with the glass fiber/epoxy or glass fiber/epoxy/silica nanoparticles or without shielding.

Poly-silicon wire for biomedical detection

After surface modification by a mixture of γ-APTES and SiO2 nanoparticles, poly-silicon wire (PSW) can be used for biomedical detection without losing much sensitivity and detection limit compared with silicon nanowire sensor. In this paper, we review the use of poly-silicon wire sensor for glucose, DNA, and cells detection.

Comparison of Memristive Behaviors of HfTiO 4 /Invar-Based Structures at Nanometer Scale

In this paper, we compare the IV behaviors of the memresistive devices with structures of HfTiO4/ITO/Invar and SiO2/HfTiO4/SiO2/Invar. The IV measurements are conducted at nanometer scale using a conductive atomic force microscopy (C-AFM). The Invar is used as a back contact during the IV measurement. After repeated set/reset bias scans, it is found that the device with structure of SiO2/HfTiO4/SiO2/Invar presents better performance in memresistive characteristics. A minimum forming current of 10 nA is needed to startup the memresistive IV behavior. Both structures are unipolar memristor suggesting that the IV behaviors are strongly correlated with the joule heat induced by the ultra-high current density in the nonoscale measurements.

FTIR Characterizations of the Gamma-Ray-Irradiated Silica Nanoparticles/γ-APTES Nanocomposite with UV Annealing

We report the effect of UV annealing on post-γ-ray-irradiated spin-coated γ-APTES and γ-APTES + NPs + UV. The structure changes of the membranes were characterized using Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM). We found that the absorption peaks of the Si-O-Si-related bonds of the FTIR spectrum varied with time after 10 kGy γ-ray irradiation. The absorption peak of the NH3 + bonds of the post-irradiated membranes showed less sensitive to hydrogen ions. The AFM surface morphologies showed great grain reconstructions after γ-ray irradiation for all the membranes. However, following the UV annealing process, both the FTIR spectrum and AFM surface morphologies showed that only the spin-coated γ-APTES + NPs + UV membrane could be restored to the pre-irradiated status. It is believed that the nanocomposite of silica NPs mixed with γ-APTES forms a lot of γ-APTES/SiO2 interfaces which enhance the post-irradiation UV oxidation and hence restore the membrane from degradation.