Fabrication and integration of planar electrodes for contactless conductivity detection on polyester-toner electrophoresis microchips

In this report, we describe the microfabrication and integration of planar electrodes for contactless conductivity detection on polyester-toner (PT) electrophoresis microchips using toner masks. Planar electrodes were fabricated by three simple steps: (i) drawing and laser-printing the electrode geometry on polyester films, (ii) sputtering deposition onto substrates, and (iii) removal of toner layer by a lift-off process. The polyester film with anchored electrodes was integrated to PT electrophoresis microchannels by lamination at 120 degrees C in less than 1 min. The electrodes were designed in an antiparallel configuration with 750 mu m width and 750 gm gap between them. The best results were recorded with a frequency of 400 kHz and 10 V-PP using a sinusoidal wave. The analytical performance of the proposed microchip was evaluated by electrophoretic separation of potassium, sodium and lithium in 150 mu m wide x 6 mu m deep microchannels. Under an electric field of 250 V/cm the analytes were successfully separated in less than 90 s with efficiencies ranging from 7000 to 13 000 plates. The detection limits (S/N = 3) found for K+, Na+, and Li+ were 3.1, 4.3, and 7.2 mu mol/L, respectively. Besides the low-cost and instrumental simplicity, the integrated PT chip eliminates the problem of manual alignment and gluing of the electrodes, permitting more robustness and better reproducibility, therefore, more suitable for mass production of electrophoresis microchips.

Fabrication of disposable voltammetric electronic tongues by using Prussian Blue films electrodeposited onto CD-R gold surfaces and recognition of milk adulteration

A new approach to fabricate a disposable electronic tongue is reported. The fabrication of the disposable sensor aimed the integration of all electrodes necessary for measurement in the same device. The disposable device was constructed with gold CD-R and copper sheets substrates and the sensing elements were gold, copper and a gold surface modified with a layer of Prussian Blue. The relative standard deviation for signals obtained from 20 different disposable gold and 10 different disposable copper electrodes was below 3.5%. The performance, electrode materials and the capability of the device to differentiate samples were evaluated for taste substances model, milk with different pasteurization processes (homogenized/pasteurized, ultra high temperature (UHT) pasteurized and UHT pasteurized with low fat content) and adulterated with hydrogen peroxide. In all analysed cases, a good separation between different samples was noticed in the score plots obtained from the principal component analysis (PCA). Crown Copyright (C) 2008 Published by Elsevier B.V. All rights reserved.

Use of copper and gold electrodes as sensitive elements for fabrication of an electronic tongue: Discrimination of wines and whiskies

A low-cost method is proposed to classify wine and whisky samples using a disposable voltammetric electronic tongue that was fabricated using gold and copper substrates and a pattern recognition technique (Principal Component Analysis). The proposed device was successfully used to discriminate between expensive and cheap whisky samples and to detect adulteration processes using only a copper electrode. For wines, the electronic tongue was composed of copper and gold working electrodes and was able to classify three different brands of wine and to make distinctions regarding the wine type, i.e., dry red, soft red, dry white and soft white brands. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.

Use of face masks by non-scrubbed operating room staff : a randomized controlled trial.

Background: Ambiguity remains about the effectiveness of wearing surgical face masks. The purpose of this study was to assess the impact on surgical site infections when non-scrubbed operating room staff did not wear surgical face masks. Design: Randomised controlled trial. Participants: Patients undergoing elective or emergency obstetric, gynecological, general, orthopaedic, breast or urological surgery in an Australian tertiary hospital. Intervention: 827 participants were enrolled and complete follow-up data was available for 811 (98.1%) patients. Operating room lists were randomly allocated to a ‘Mask roup’ (all non-scrubbed staff wore a mask) or ‘No Mask group’ (none of the non-scrubbed staff wore masks). Primary end point: Surgical site infection (identified using in-patient surveillance; post discharge follow-up and chart reviews). The patient was followed for up to six weeks. Results: Overall, 83 (10.2%) surgical site infections were recorded; 46/401 (11.5%) in the Masked group and 37/410 (9.0%) in the No Mask group; odds ratio (OR) 0.77 (95% confidence interval (CI) 0.49 to 1.21), p = 0.151. Independent risk factors for surgical site infection included: any pre-operative stay (adjusted odds ratio [aOR], 0.43 (95% CI, 0.20; 0.95), high BMI aOR, 0.38 (95% CI, 0.17; 0.87), and any previous surgical site infection aOR, 0.40 (95% CI, 0.17; 0.89). Conclusion: Surgical site infection rates did not increase when non-scrubbed operating room personnel did not wear a face mask.

Two-Dimensional Encoding Masks ror Hadamard Spectrometric Imager

Techniques to improve upon the design of two-dimensional encoding masks for multiplex Hadamard spectrometric imagers are described. The technique to generate masks based on completely orthonormal codes is described. In some cases, selfsupporting masks result which were not previously known. Transmission through the encoding masks (but not necessarily the signalto-noise ratio) can also be increased.

Suspended multiwalled carbon nanotubes as self-aligned evaporation masks

We describe the nanofabrication study of self-aligned electrodes on suspended multiwalled carbon nanotube structures. When metal is deposited on a suspended multiwalled carbon nanotube structure, the nanotube acts as an evaporation mask, resulting in the formation of discontinuous electrodes. The metal deposits on the nanotubes are removed with lift-off. Using Al sacrificial layers, it was possible to fabricate self-aligned contact electrodes and control electrodes nanometers from the suspended carbon nanotubes with a single lithography step. It was also shown that the fabrication technique may also be used to form nano-gapped contact electrodes. The technique should prove useful for the fabrication of nano-electromechanical systems.

Optimized phase pupil masks for extended depths of field

By properly designing a phase pupil mask to modulate or encode the optical images and then digitally restoring them, one can greatly extend the depth of field and improve image quality. The original works done by Dowski and Cathey introduce the use of a cubic phase pupil mask to extend the depth of field. The theoretical and experimental researches all verified its effectiveness. In this paper, we suggest the use of an exponential phase pupil mask to extend the depth of field. This phase mask has two variable parameters for designing to control the shape of the mask so as to modulate the wave-front more flexible. We employ an optimization procedure based on the Fisher information metric to obtain the optimum values of the parameters for the exponential and the cubic masks, respectively. A series of performance comparisons between these two optimized phase masks in extending the depth of field are then done. The results show that the exponential phase mask provide slight advantage to the cubic one in several aspects. (c) 2006 Elsevier B.V. All rights reserved.