Analog signal acquisition from computer optical disk drives for quantitative chemical sensing

Optoelectronic consumer products that are widely employed in the office and home attract attention for optical sensor applications due to (1) their cost advantage over analytical instruments produced only in small quantities, (2) robustness in operation due to the detailed manufacturability improvements, and (3) ease of operation. We demonstrate here a new approach for quantitative chemical/biochemical sensing when analog signals are acquired from conventional optical disk drives, and these signals are used for quantitative detection of optical changes of sensor films deposited on conventional CD and DVD optical disks. Because we do not alter manufacturing process of optical disks, any disk can be employed for deposition and readout of sensor films. The optical disk drives also perform their original function of reading and writing digital content to optical media because no optical modifications are introduced to obtain the analog signal. Such a sensor platform is quite universal and can be applied for chemical and biological quantitative detection, as well as for monitoring of changes of physical properties of regions deposited onto a CD or DVD (e.g., during combinatorial screening of materials). As a model example, we demonstrate the concept using chemical detection of ionic species such as Ca2+ in liquids (e.g., blood, urine, or water). Colorimetric calcium-sensitive sensor films were deposited onto a DVD, exposed to water with different concentrations of Ca2+, and quantified in the optical disk drive. The developed lab-on-DVD system demonstrated a 5 ppm detection limit of Ca2+ determinations, similar or slightly better than that achieved using a conventional fiber-optic portable spectrometer. This detection limit corresponded to a 0.023 absorbance unit resolution, as determined by the measurement of the same colorimetric films with a portable spectrometer. Determinations of Ca2+ unknowns using the lab-on-DVD system demonstrated +/-5 ppm accuracy and 2-5% relative standard deviation precision in predicting 100 ppm Ca2+.     

Vector diffraction analysis of optical disk readout

The optical disk readout signals from ROM disks are presented by use of a rigorous three-dimensional vector diffraction method. The optical disk is modeled as a crossed metal grating without restriction on the form of the information marks, and the permittivity of the metal is taken into account. The diffracted field from the disk is obtained by means of decomposing the focused incident beam into a spectrum of plane waves and then calculating the diffracted plane waves for each respective incident component. The readout signal is obtained by integration of the energy-flux density of the diffracted field according to the detection scheme of the optical disk system. A typical digital versatile disk (DVD) system is applied with this theory, and the result is far from that of scalar diffraction theory.     

Formation of nanometer-scale structures using conventional optical lithography

We investigated a new method to form the line-and-space patterns with a nanometer-scale using the conventional optical lithography technique and the metal deposition/liftoff process. The ashing of the negative photo resist defined by the conventional optical lithography technique results in the proper profiles including a high aspect ratio (i.e., height/width value of the patterns) for the formation of nanometer-scale structures. We demonstrated that the metal electrodes with the nanometer-scale gap of 20 nm or less can be easily obtained by the newly proposed method without employing the highly sophisticated lithography tools including an electron beam lithography.     

Performance analysis of a multimode waveguide-based optical disk readout system

We propose a method to improve the optical resolution to read out optical disks, without making the spot size on the disk smaller than the diffraction limit. The idea is to reconstruct the bit pattern from the complete field profile (including amplitude and phase) of the light reflected from the disk. We measure the phase and amplitude information by picking up the wave front into different modes of a bimodal waveguide. Once picked up, these modes can be split by a photonic integrated circuit to be measured by separate detectors. By combining the information from the responses from the different modes, we can improve the bit error rate substantially.     

Portable and quantitative detection of protein biomarkers and small molecular toxins using antibodies and ubiquitous personal glucose meters

Developing portable and low-cost methods for quantitative detection of large protein biomarkers and small molecular toxins can play a significant role in controlling and preventing diseases or toxins outbreaks. Despite years of research, most current methods still require laboratory-based or customized devices that are not widely available to the general public for quantitative analysis. We have previously demonstrated the use of personal glucose meters (PGMs) and functional DNAs for the detection of many nonglucose targets. However, the range of targets detectable by functional DNAs is limited at the current stage. To expand the range of targets that can be detected by PGMs, we report here the use of antibodies in combination with sandwich and competitive assays for quantitative detection of protein biomarkers (PSA, with a detection limit of 0.4 ng/mL) and small molecular toxins (Ochratoxin A, with a detection limit of 6.8 ng/mL), respectively. In both assay methods, with invertase conjugates as the link, quantitative detection is achieved via the dependence between the concentrations of the targets in the sample and the glucose measured by PGMs. Given the wide availability of antibodies for numerous targets, the methods demonstrated here can expand the range of target detection by PGMs significantly.     

Evaluation of adequacy of quantitative laboratory chemical analysis techniques

According to GOST R ISO/IEC 17027, evaluation of adequacy of testing (analysis, measurements) techniques is a constituent element of laboratory technical competence. The stages of the work performed when evaluating adequacy of quantitative chemical analysis techniques, the range of determined metrological characteristics, and the ways of their presentation depending on the applied algorithms of evaluating the precision parameters of analysis techniques are considered. It is shown that, for the majority of the analysis techniques applied in accordance with the requirements of the regulating normative documents (ND), Russian practice of development, certification, and acceptance tolerance for measurement techniques does not necessitate a laboratory procedure of adequacy evaluation. As far as these techniques are concerned, the possibility of correctly using them in laboratory conditions is verified prior to their application for work sample analysis. Algorithms demonstrating the adequacy (experimentally verified compliance) of the analysis performed in laboratory conditions to documented requirements are recommended.     

Fabrication of piezoelectric ceramic micro-actuator and its reliability for hard disk drives

A new U-type micro-actuator for precisely positioning a magnetic head in high-density hard disk drives was proposed and developed. The micro-actuator is composed of a U-type stainless steel substrate and two piezoelectric ceramic elements. Using a high-d31 piezoelectric coefficient PMN-PZT ceramic plate and adopting reactive ion etching process fabricate the piezoelectric elements. Reliability against temperature was investigated to ensure the practical application to the drive products. The U-type substrate attached to each side via piezoelectric elements also was simulated by the finite-element method and practically measured by a laser Doppler vibrometer in order to testify the driving mechanics of it. The micro-actuator coupled with two piezoelectric elements featured large displacement of 0.875 microm and high-resonance frequency over 22 kHz. The novel piezoelectric micro-actuators then possess a useful compromise performance to displacement, resonance frequency, and generative force. The results reveal that the new design concept provides a valuable alternative for multilayer piezoelectric micro-actuators.     

Enhanced sensitivity of chemical dosimeters using liquid-core optical waveguides

The spectrophotometric sensitivity of chromophoric chemical dosimeters can be enhanced by increasing the optical path length through the light absorbing medium. This approach is used with optical waveguide (OWG) dosimeters, consisting of liquid-phase light-propagating media filling the core of a long, thin flexible polymer tubing. The liquid phase consists of dimethyl sulfoxide, N, N,-dimethylformamide, or triethyl phosphate solutions of hexa (hydroxyethyl) pararosaniline cyanide, a wellknown radiochromic dye precursor, which on irradiation converts from the leucoform into a brightly colored dye chromophore. The experimental design is described, as well as the influences of some experimental parameters: length of the OWG, curvature of the waveguide loops, cross section of the liquid light-guiding core, the temperature and the solvent. It was shown that concentrations of the radiation-generated dye as low as 5 × 10⁻⁸ mol dm⁻³ (corresponding to absorbed doses of about 10 mGy) can be measured on a standard spectrophotometer using a 100 cm long waveguide. It was also shown that sensitivity (optical absorbance increase per unit length per unit dose) was the same whether the light passed on a straight path or through a multiply looped waveguide as long as 150 cm. It is suggested that such long OWG assemblies can be used for enhancing the response of chemical dosimeters for medical and radiation protection applications, as well as in analytical chemistry and for chemical kinetics studies.     

Theoretical analysis of a thermally induced superresolution optical disk with different readout optics

Simulations have been performed to evaluate the effect of a thermal-induced mask on the performance of an optical disk. For simplicity and also so as not to lose generality, we first assume that the thermal-induced mask can be represented by an ellipse with variable shape and a relative position with respect to the center of the readout laser spot. Simulation results reveal that the optical disk exhibits a maximum response when almost half the laser spot is covered by the mask. With a conventional single-beam readout technique, however, this can hardly be achieved. The possibility of achieving this by use of an assistant beam with a modified beam profile is discussed. We show that this method allows us to obtain a maximum response in the track direction without any degradation in the radial direction.     

Theory and practice in measuring wood grain angle using microwaves

Knowledge of wood grain inclination is critical for achieving improved lumber strength grading. This paper describes an instrumentation system and theory for using microwaves to measure wood grain angle in real time. By using an electrically modulated scattering dipole with a homodyne microwave system, it is found both theoretically and experimentally that the amplitude reading of the modulated scattered signal provides an excellent means far measuring wood grain angle. In addition, the phase output of the system can be used to identify the sign of the grain angle. Two widely used wood species, Douglas Fir and Spruce, are measured at different moisture levels to verify the theoretical prediction experimentally. Preliminary data analysis shows that reliable measurement of grain angles up to about 30° can be made for wood within a wide range of specific gravity and moisture content. Through the experimental measurements, the potential of such a system for industrial use is demonstrated     

A mixed-mode crack analysis of rotating disk using finite element method

This paper presents a rigorous elastodynamic hybrid-displacement finite element procedure for a safety analysis of fast rotating disks with mixed-mode cracks. Based on a modified Hamilton's principle, the finite element model is derived such that the proper crack-tip singularities are taken into consideration and the interelement displacement compatibility conditions are still satisfied. Thus, the specimen can be represented by a finite element assemblage in which “singular” elements are used around the crack-tip and high-order isoparametric “regular” elements are taken elsewhere.To determine the mixed-mode stress intensity factors, the modified $\text{J}\text{?}{}_{\mathrm{k}}$ integrals for rotating cracked disks have been established taking into account the effect of centrifugal force. Using the “strain-energy-density factor” concept, the direction of crack growth of a rotating disk with an arbitrary internal crack is predicted. To provide a method of non-destructive testing in evaluating the integrity of structures, natural vibrations of cracked disk are then studied. Lastly, the influence of inertia effects due to rotating speed changes in determining the dynamic stress intensity factors is examined.For verification purposes, the simple case of a rotating disk with radial cracks is first solved. Excellent correlations between the computed results and available referenced solutions are drawn. New solutions for the circular disk with circumferential or arbitrarily-oriented cracks are also presented.     

Evaluation of test procedures for determining servo compatibilityof heads and media in magnetic disk drives

We evaluate a testing specification proposed by the National Storage Industry Consortium's (NSIC) Extremely High Density Recording (EHDR) group for evaluating head and media compatibility for servo performance in magnetic disk drives. These tests use average amplitude and average noise profile measurements across isolated tracks to predict the shape, linearity, noise, and long-term stability of position error signal (PES) patterns. We compare the predictions from these tests to measurements from null and amplitude PES patterns written on a spin-stand. Results show average PES-profile prediction errors of 1%-2% track width and noise level prediction within a factor of 2. We present data from tests for long-term stability of the magnetoresistive (MR) read element after repeated write cycles by the inductive write head. In the set of heads we tested, the MR head's center and effective width changed only slightly. Although we evaluated the NSIC specification for MR read elements, the specification should be equally valid for other read head types also, as long as the PES patterns are similar     

Strain imaging using conventional and ultrafast ultrasound imaging: numerical analysis

In elasticity imaging, the ultrasound frames acquired during tissue deformation are analyzed to estimate the internal displacements and strains. If the deformation rate is high, high-frame-rate imaging techniques are required to avoid the severe decorrelation between the neighboring ultrasound images. In these high-frame-rate techniques, however, the broader and less focused ultrasound beam is transmitted and, hence, the image quality is degraded. We quantitatively compared strain images obtained using conventional and ultrafast ultrasound imaging methods. The performance of the elasticity imaging was evaluated using custom-designed, numerical simulations. Our results demonstrate that signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and spatial resolutions in displacement and strain images acquired using conventional and ultrafast ultrasound imaging are comparable. This study suggests that the high-frame-rate ultrasound imaging can be reliably used in elasticity imaging if frame rate is critical     

Measurement uncertainty in quantitative chemical analysis: Problems of the transition period

Various aspects of the implementation of the concept of measurement uncertainty in analytical laboratories of Russia are considered. Information on international and identical domestic documents on the estimation and application of measurement uncertainty is presented. The analogy between the transition to the uncertainty concept and the transition to the metric system is drawn.     

Quantitative analysis of historical mortars using optical microscopy

As a part of the activities of the RILEM TC 167-COM committee two methods of quantitative microscopy have been developed for analysing historical mortars. This paper gives background information for the application of these methods. The methods concern the determination of mix proportions and aggregate size distribution using microscopical methods. A method is also described for correcting determinations of mix proportions based on chemical analysis of acid-soluble calcium oxide for the presence of carbonate in the aggregate.

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Résumé Dans le cadre des activités de la Commission RILEM TC 167-COM, deux méthodes de microscopie quantitative ont été développées pour l’analyse des mortiers historiques. Ce document donne des informations sur les antécédents de l’application de ces méthodes. Celles-ci concernent la détermination des proportions de mélanges et la répartition des tailles des appareils en utilisant la méthode microscopique. Une méthode est également décrite pour la correction des déterminations des proportions de mélanges, à partir de l’analyse chimique de l’oxyde de calcium soluble dans l’acide pour déterminer la présence de carbonate dans l’appareil.

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TC MEMBERSHIP: Chairman: Caspar Groot, the Netherlands.Secretary: Geoff Ashall, UK.Members: Giulia Baronio, Italy; Peter Bartos, UK; Luigia Binda, Italy; Kristof Callebaut, Jan Elsen, Belgium; Rob van Hees, the Netherlands; John Hughes, UK; Loek van der Klugt, the Netherlands; Jan Erik Lindqvist, Sweden; Elisabeth Marie-Victorie, France; Bernhard Middendorf, Germany; Ioanna Papayianni, Greece; Margaret Thomson, USA; Eleni-Eva Toumbakari, Greece; Alf Waldum, Norway.     

COM-C1 Assessment of mix proportions in historical mortars using quantitative optical microscopy

RILEM Technical CommitteesRILEM TC 167-COM: Characterization of old Mortars Recommendations

COM-C1 Assessment of mix proportions in historical mortars using quantitative optical microscopy     

Magneto-optical disk drive technology using multiple fiber-coupled flying optical heads. Part I. System design and performance

A novel flying-optical-head data storage technology is described. It is based on a micro-optical recording head that contains a silicon micromachined torsional mirror for high-bandwidth track following. Multiple heads and disks are contained in a Winchester-style rotating disk drive. Single-mode optical fibers provide light delivery to and from the heads. Both polarization-maintaining and low-birefringence fiber systems have been implemented for magneto-optical (MO) recording. A fixed optics module containing a laser diode, MO detection optics, and a 1 x N fiber bundle switch has been developed as an integral part of this new recording architecture. A 5.25-in. (13.33-cm), half-height prototype drive design and its performance are presented.     

Integration of polymer waveguides for optical detection in microfabricated chemical analysis systems

Multimode polymer waveguides and fiber-to-waveguide couplers have been integrated with microfluidic channels by use of a single-mask-step procedure, which ensured self-alignment between the optics and the fluidics and allowed a fabrication and packaging time of only one day. Three fabrication procedures for obtaining hermetically sealed channels were investigated, and the spectrally resolved propagation loss (400-900 nm) of the integrated waveguides was determined for all three procedures. Two chemical absorbance cells with optical path lengths of 100 and 1000 microm were furthermore fabricated and characterized in terms of coupling loss, sensitivity, and limit of detection for measurements of the dye bromothymol blue.