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The photoreduction of toxic Cr(VI) to environmental Cr(III) driven by visible-light is highly desired. Metal-organic frameworks (MOFs), as one class of outstanding porous materials, had been utilized for photoreduction of Cr(VI). Current methods modulated the photoreduction of Cr(VI) mainly by selection of suitable metal ions or organic ligands in single component MOFs. However, most of them still exhibit limited photoreduction performance due to low Cr(VI) adsorption rate/capacity, weak light harvesting efficiency, and/or poor electronic utilization efficiency. Multivariate metal-organic frameworks with highly visible-light photosensitive unit and strong Cr(VI) adsorption strut into one single phase is therefore expected to be an effective strategy to improve the photoreduction of Cr(VI), but remains unexplored. Herein, intense visible-light absorption porphyrin unit and strong toxic anions adsorption strut were integrated into one single MOF simultaneously via a sequential mixed-ligand and ionization method, which strongly improve the photoreduction performance of Cr(VI). The synergistic effect of strong adsorption of Cr2O72− and efficient utilization of light endowed H2TCPP⊂(I-)Meim-UiO-66 with highly efficient photoreduction activity toward toxic Cr2O72− under visible light in a rate of 13.3 mgCr(VI)/gcatalyst/min, much higher than the reported MOF-based photocatalysts including typical NH2-UiO-66 (0.2 mgCr(VI)/gcatalyst/min) and NH2-MIL-125 (1.6 mgCr(VI)/gcatalyst/min). As far as we know, this is the best catalyst among all the reported MOF-based photocatalysts for Cr(VI) photoreduction, in which the I- in our imidazolium functionalized MOF acts as sacrificial agent. Based on the results from time-resolved photoluminescence spectra, electron spin resonance, and theoretical calculation etc., a photoreduction mechanism of Cr2O72- over H2TCPP⊂(I-)Meim-UiO-66 was also well proposed. This general and facial strategy, combining the advantages of adsorption and photosensitivity in a multivariate MOF, paves the way to design of higher efficient photocatalytic materials.

Inductively coupled plasma reactive-ion etching (ICP-RIE) is first applied to decrease the thickness of a Si substrate for light-addressable potentiometric sensor (LAPS) characterization. A simple and reliable process flow with the self-aligned Al layer as a hard mask layer in ICP-RIE is used to fabricate a thin semiconductor substrate with Al back-side contact. A single-side polished P-type Si wafer with a thickness of 350 μm is decreased to 100 μm by ICP-RIE from the polished side. The thickness of the thin Si substrate and the dimensions of the designed patterns determined by ICP-RIE are verified using scanning electron microscopy (SEM) and an optical microscope (OM). A selective high-dielectric constant insulator, niobium oxide (NbOx), is directly deposited on the unpolished side of the thin Si substrate as the sensing membrane of a LAPS by reactive ratio frequency (rf) sputtering. A high photocurrent was found in the ICP-RIE LAPS sample under back-side illumination, particularly in high-frequency operation. Compared to an Si substrate without ICP-RIE, 3-fold and 6.5-fold higher photocurrents were achieved by the proposed LAPS with ICP-RIE measured at 1 and 50 kHz of light modulated frequency, respectively. The highest modulated frequency of illumination was 50 kHz for an acceptable photocurrent in the LAPS with ICP-RIE, which is sufficient for two-dimensional (2D) images acquired with high-speed scanning. The NbOx layer deposited on the unpolished Si surface could automatically generate higher pH sensitivity than conventional polished Si surfaces because of the higher surface roughness. The calculated pH sensitivity and linearity were 55.8 mV/pH and 99.6%, respectively, in a pH range from 2 to 12. No clear degradation of hysteresis was found for the LAPS with ICP-RIE. For the designed patterns of the Al hard mask layer, the spatial resolution of the 2D image of the LAPS with ICP-RIE could be obtained by the difference between dimensions observed by OM and the dimensions calculated from the photocurrent versus scanning length controlled by the X-Y stage. A pattern with a length of 250 μm generated by ICP-RIE was measured as 255 μm in the LAPS with scanning step of 5 μm. ICP-RIE is demonstrated to achieve a spatial resolution of 5 μm in the Si-based LAPS. Further reduction of the thickness of an Si substrate by ICP-RIE controlling and its ability to create a dynamic 2D image are suggested for future investigation in spatial resolution optimization.

A fully integrated system and user interface, named Mirror-LAPS, was established for chemical imaging of diffusion-based reactions and bioimaging, e.g., cellular metabolism imaging in situ, with advantages of portability, real-time monitoring and flexible control. By means of a field programmable gate array (FPGA), a minimized drive circuit and an illumination path integrated into the hardware, the volume and cost of this Mirror-LAPS system are only 11 % and 75 %, respectively, those of the conventional LAPS system. 2D images can be easily constructed based on the combination of the measured photocurrent with automatic digitization and recorded coordinates for each pixel in the frame. The time to image one pixel under the optimized parameters with a periods per pixel (PPP) of 64 is approximately 6.6 ms. The location, area, and resolution of pixels can be easily, quickly and flexibly adjusted in the user interface to obtain 2D images and a real-time video. The cellular metabolism of HK2 cellsfor different cell numbers and glucose concentrations is virtually demonstrated by this Mirror-LAPS system by the color changes in 2D images for the first time, which could provide a reliable platform in a cell culturing space for cell-based research.

Amorphous silicon (a-Si) has been approved for use as the semiconductor layer in a light-addressable potentiometric sensor (LAPS). A new device structure of niobium oxide (NbOx)/P-I-N amorphous silicon (a-Si) on ITO/glass is proposed for a thin film LAPS with the advantage of a high photovoltage. P-type, intrinsic and N-type a-Si layers are fabricated by plasma enhanced chemical vapor deposition (PECVD) with selective gas dopants on ITO/glass. A single NbOx layer is directly sputtered onto an a-Si substrate and is used as the pH sensing membrane. The temperatures for all of the processes used to manufacture this device are lower than 300 °C, including the rapid thermal anneal (RTA) treatment, which is compatible with conventional fabrication processes for glass substrates in solar cells and thin film transistors. Based on the photovoltage versus gate bias characteristics in standard buffer solutions, the calculated pH sensitivity and linearity from pH 2 to 10 is 40 mV/pH and 99.4% for the P-I-N a-Si LAPS with RTA treatment at 300 °C. Compared with an intrinsic a-Si structure, a 50% higher photovoltage is achieved in the P-I-N a-Si LAPS. Furthermore, XRD and SIMS are used to verify the properties of the a-Si film. A high frequency ac laser signal of up to 20 kHz was obtained with the P-I-N a-Si LAPS while maintaining the same spatial resolution, which is important for two-dimensional images acquired by high-speed scanning with an analog micromirror.

Indium Gallium Zinc Oxide (IGZO) on Indium Tin Oxide (ITO) glass has been applied as the semiconductor substrate of a light-addressable potentiometric sensor (LAPS) with the advantages of immunity to room light inference and high photocurrent. For the first time, investigations into this IGZO LAPS including two-dimensional (2D) chemical imaging and reduction of the potential biorelative damage induced by the requirement of an ultraviolet (UV) light source are presented in this study. For the spatial resolution, a smaller aperture for the light spot provided by a light emitting diode (LED) makes the photocurrent decrease. To overcome this natural limitation, the type of AC modulation of light source is changed from a sine wave to a square wave with different duty cycles. The photocurrent and power consumption of a 365 nm LED with square wave and a duty cycle of 40 % are 42.2 % higher and 16.2 % lower than those of the conventional setup of a sine wave, respectively. The pH sensitivity, linearity, hysteresis and drift are comparable. The illumination wavelengths of 365, 405 and 435 nm are studied for photoresponse. 405 nm illumination with acceptable pH sensing performance can be suggested for IGZO LAPS for less bio damage concern. Additionally, a laser with a wavelength of 405 nm with spot size of 25 μm and scanning step of 2 μm is proven to have a clear pattern recognition down to 50 μm in 2D image. Further optimization of the spot size of the laser, thickness and composition of IGZO are suggested for better spatial resolution.

Sweat rate monitor is an important factor for hydration in exercise and training. However, the measurement of sweat rate is complicated and time-consumption in the conventional method by a calculation of total weight loss. Sweat sensor is a potential candidate to overcome these drawbacks, which may be possible to use in wearable applications for continuous detection. In the study, a new capacitive-type sensor constructed by Gui diatomaceous earth (GDE) is first proposed for solution volume detection in μl level on flexible substrate. Solution can easily penetrate into GDE through the top electrode with interdigital patterns. Capacitance is increased with volume of RO water, which can be explained by increases of dielectric constant and response area after water penetration. Sensitivity is about 7.2 pF/μl and application volume range is from 2 to 8 μl, which is a potential candidate for human sweating rate test in the future.

Two in-vacuum kicker magnets serve to inject and to extract the electron beams for the TPS injector. A large gas load generated from the outgassing of kicker ferrites (CMD5005) causes concern. To study the effect of vacuum firing in decreasing the outgassing from kicker ferrites, we set up a test bench to record spectra from a residual-gas analyzer (RGA) and measured the rates of outgassing during vacuum firing. The RGA spectrum revealed that water vapor is the dominant gas from the unbaked ferrites; with the throughput method the rate of outgassing, q2.7 (Ferrite), before baking was 5.5 × 10−9 mbar L s−1 cm−2. A duration 40 h of vacuum firing at 200 °C is required to remove the water vapor from the kicker ferrites and to yield a rate between 2.2 × 10−12 and 2.6 × 10−12 mbar L s−1 cm−2 after vacuum firing.

For higher photo signal of chemical image sensor, a new device structure of P-I-N amorphous silicon (a-Si) on ITO/glass is first applied in light-addressable potentiometric sensor (LAPS). Niobium oxide (NbO x ) is used as pH sensing membrane. All processes of device are lower than 300 o C, which are suitable for glass substrate. Based on photovoltage versus gate bias characteristics, calculated pH sensitivity and linearity between pH 2 to 10 is 40 mV/pH and 99.4%, respectively. Compare to conventional intrinsic amorphous silicon structure, improvement on photocurrent, and spatial resolution are 50% and 15%, respectively. In the meantime, higher frequency of ac signal of laser up to 20 kHz could be used for high speed scanning by means of red laser and analog micromirror scanning system.

In this study, a tin-based oxide (SnOx) semiconductor layer on a commercial indium tin oxide (ITO)/glass substrate was investigated for the first time for use as the active layer of a light-addressable potentiometric sensor (LAPS). The photoabsorption of SnOx layers sputtered using varying Ar/O2 gas flow ratios was characterized by means of the ultraviolet–visible spectroscopy (UV–Vis); the photo/electric response of a LAPS directly covered with an NbOx sensing membrane was evaluated under modulated ultraviolet illumination. In situ substrate heating at 250 °C during sputtering and post-deposition rapid thermal annealing (RTA) with temperatures of 400 and 450 °C in a N2 environment were applied to study sample behavior. Based on X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results, the fabricated SnO2 layer can be transformed into a polycrystalline SnO2 phase in the bulk with a surface SnO layer by thermal budget. A high photocurrent and an acceptable pH sensitivity of 1.29 μA and 57.6 mV/pH, respectively, are obtained under UV light-emitting diode (LED) illumination for a LAPS built using a SnOx layer sputtered with a flow ratio of Ar/O2 = 46/4 with substrate heating at 250 °C. The stability and lifetime performance of the SnOx LAPS needs to be improved by further process optimization, especially in terms of developing a crack-free SnOx process and increasing sensing membrane coverage. The experimental results show the potential of SnOx for use as the active layer in a LAPS.

A fracture mechanics based numerical approach is developed for modeling delamination growth on materials interfaces in integrated circuit (IC) interconnects. In this approach, the heterogeneous interconnect structures neighboring the cracked interface are approximated by homogenized layers with transversely isotropic elastic properties. Evolution of the interface crack under fatigue condition is modeled by using an incremental approach, in which the fracture mechanics parameters including the strain energy release rate, the normalized stress intensity factors and phase angles are first estimated by post-processing finite element solutions. The fracture mechanics parameters along the curvilinear front of the interface crack are then substituted into a steady-state fatigue crack growth model for obtaining the crack growth increments. The process is repeated to simulate subsequent crack growth for predicting interconnect structural reliability under fatigue condition. The evolution of an interface corner crack in a back-end-of-line (BEOL) Cu/low-k interconnect structure under temperature cycling condition is considered as an application example of the procedure.

The spectroscopic, electrochemical and electroluminescent properties of three binuclear Ru(II) complexes with different length of flexible bridges were investigated. The single-layer electroluminescent devices with configuration of indium–tin oxide/Ru complex (~ 100 nm)/Ga:In were found to give a turn-on voltages as low as 2.3 V, a maximum luminance up to 310 cd/m2 at a bias voltage of 5.8 V, and low delay times less than 2 s.

This study describes magnetically driven suppression of cross-reactions among molecules. First, the magnetic nanoparticles are coated with bio-probes and dispersed in liquid. The bio-probes can then bind with homologous or heterologous bio-targets. When alternating-current (ac) magnetic fields are applied, magnetic nanoparticles rotate driven by ac magnetic fields. Thus, the bio-targets bound on the surface of magnetic nanoparticles experience a centrifugal force. The centrifugal force can be manipulated by adjusting the angular frequency of the rotating magnetic nanoparticles. The angular frequency is determined by the applied ac magnetic field frequency. Since the binding force for good binding is much higher than that of poor binding, frequency manipulation is needed for the centrifugal force to be higher than the poor-binding force but lower than the good-binding force. Therefore, poor binding which contributes to cross reactions between molecules can be suppressed efficiently by control of the ac magnetic field frequency.

Immunomagnetic reduction (IMR), which involves measuring the reduction in the ac magnetic susceptibility of magnetic reagents, is due to the association between bio-functionalized magnetic nanoparticles and target bio-molecules. This has been demonstrated for assaying proteins in solutions free of Fe ions, such as serum. In this work, the validity of IMR assay for samples rich in Fe ions like hemoglobin (Hb) is investigated. According to the results, there is no magnetic signal contributed by Fe-ion-rich Hb. Furthermore, the results show a high sensitivity in assaying hemoglobin A1c (HbA1c) by using IMR.

The influence of the initially ordered state to the structural evolution on the magnetic fluid film under perpendicular magnetic fields was investigated. The magnetic field was increased from zero to a certain strength H i at a given sweep rate d H /d t and maintained at H i for a period of time, after which the magnetic field was further raised at d H /d t . The H i was adequately set so that a granular ordered structure of magnetic columns formed in the magnetic fluid film. This granular ordered structure served as an initial state for the following structural evolution when the magnetic field was increased from H i . When the magnetic field was raised up to H s , the structure evolved to the transition state, at which each column split into two columns. To obtain the initial structures of various orderness, the duration time t d at H i was varied from 1 to 180 s. It was found that the degree of orderness of the initial structure under H i increases with t d , and a higher H s was also observed. This result can be interpreted by taking the interactions between a column and its neighbors into account.

Influences of both the magnetic field strength H and the sweep rate d H /d t on the structural pattern evolution in a magnetic fluid film under perpendicular fields are systematically investigated. When the magnetic field is increased at a given rate, the structure evolves from a monodispersed state to a disordered one, then to the first-level ordered hexagonal structure, and finally to the second-level ordered structure through a transition state. With a higher d H /d t , the range of the applied magnetic field corresponding to the first-level ordered structure is widened and the field H s , at which the transition occurs becomes higher. An empirical power law H s ∝(d H /d t ) 0.4 was found. A phase diagram for the magnetic fluid film in the H –d H /d t plane is presented.

In this work, the influence of the sweep rates of applied magnetic fields on the agglomeration of magnetic particles in the magnetic fluid film are reported. It was observed that a smaller column agglomerated by magnetic particles results at a higher sweep rate as compared with that at a lower sweep rate. Besides, the magnetic moment per volume inside a column decreases rapidly when the sweep rate is raised from 0 to 15 Oe/s, and almost remains constant as the sweep rate exceeds 20 Oe/s. This variation implies that the packing of magnetic particles inside a column depends on the sweep rate. Thus, the sweep rate is a crucial variable determining the internal structure of columns.