www.flowinjectiontutorial.com

www.flowinjectiontutorial.com

The 5^th edition of The Tutorial, now accessible on line comprises: 

• Preface, discussing revolution taking place in scientific publishing 
• Introduction, reviews development of methods of flow analysis, beginning with air segmented systems, focuses on flow programming, and concludes with high throughput Sequential Injection technique.
• Theory deals with mixing by dispersion in flow system, emphasizing  the essential role of the turbulent flow. 
• Methods section deals with Flow Injection, Sequential Injection, Bead Injection and Sequential Injection Chromatography, illustrated by examples of work from world leaders in the field.  
• FIA Story is collection of contributions written by those, who participated in inventing, advancing and commercialization of Flow Injection and related techniques. This multicolor quilt of stories is the heritage from which much is to be learned about science, discovery and commerce. 
• Database contains over 22000 instantly searchable references. 
• News section comprises announcements of forthcoming meetings and publications from the field of analytical chemistry. 

Contributions related to flow analysis and instrumentation are cordially invited, and will be published free of charge, with the exception of commercials. The website is financially supported by the author.

2014 Bunsen-Kirchhoff Award for Analytical Spectroscopy

Annoucement

The DASp – German Working group for Applied Spectroscopy - regularly awards the "Bunsen-Kirchhoff-Preis für analytische Spektroskopie" to honour preferably the work of young scientists from universities, research institutes or industry who made excellent contributions to analytical spectroscopy. Especially preferred is an oeuvre in new areas like spectroscopy in nano compartments, spectroscopy of biomolecules a.s.o. The Award consists of an award-document and an amount of € 2.500,00 sponsored by Perkin Elmer and the DASp seeks nominations for the 2014 Bunsen-Kirchhoff Award for Analytical Spectroscopy. The Award will be presented at the Analytica in April 2014 in Munich (Germany).

A nomination (in electronic form) should include:

  1. letter with the candidate´s accomplishments

  2. list of publications or recent work,

  3. scientific curriculum vitae stating the age of the candidate; the candidate´s address, phone fax and e-mail.

Nominations can be made by members of DASp but eligibility is open for any scientist meeting the requirements. Self-nomination is excluded. The decision as to whom the prize is to be awarded shall be made by a jury consisting of the current members of the board of DASp.

Further information is available at:

https://www.gdch.de/netzwerk-strukturen/fachstrukturen/analytische-chemie/arbeitskreise/ak-dasp.html

All documents should be sent not later than 15 December 2013 to: Prof. Dr. Detlef Günther, President of the Jury for the Bunsen-Kirchhoff Award 2014, ETH Zürich, Laboratorium für Anorganische Chemie, Wolfgang-pauli-Str. 10, HCI G113, CH-8093 Zürich (Schweiz) 

E-Mail: Secretary, Ms Nicole Bachmann (nbachmann@inorg.chem.ethz.ch

Just Published: Sensors & Actuators B: Chemical

A new issue of this journal has just been published. To see abstracts of the papers it contains (with links through to the full papers) click here:

Sensors & Actuators B: Chemical
http://rss.sciencedirect.com/publication/science/5283

Selected papers from the latest issue:

A novel way for detection of eugenol via poly (diallyldimethylammonium chloride) functionalized graphene-MoS2 nano-flower fabricated electrochemical sensor

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Qingliang Feng , Kaiyue Duan , Xiaoliang Ye , Daban Lu , Yongling Du , Chunming Wang
Poly (diallyldimethylammonium chloride) functionalized graphene-MoS2 nano-flower materials (PDDA-G-MoS2) were successfully synthesized, in which the addition of MoS2 wrinkling the graphene further increased the specific surface area. Then, the gold nanoparticles (AuNPs) were assembled on the surface of PDDA-G-MoS2 via electrostatic attractive force and function of AuS bond. The obtained Au/PDDA-G-MoS2 nanomaterial was used to modify glassy carbon electrode (Au/PDDA-G-MoS2/GCE) and determine sensitively eugenol. The oxidation peak currents increased distinctly on the proposed electrochemical sensor by cyclic voltammetry (CV) in 0.10molL⁻¹ NaAc-HAc buffer solution (pH=5.50), indicating that the material shows excellent electrochemical properties. The reaction kinetics was studied and the experimental conditions were optimized. The oxidation peak current of eugenol increased linearly with addition of concentration in the range from 0.1 to 440μmolL⁻¹ with a low detection limit of 0.036μmolL⁻¹ (S/N =3). This sensor exhibited high sensitivity, good stability and fast responses, and also has been applied to determination of eugenol in real samples with satisfactory results. The novel PDDA functionalization graphene-MoS2 nanoflower shows excellent electrocatalysis for determination of eugenol and satisfactory dispersity in water than graphene; these would show its potential application in analysis, medical science and nanodevice field via combining graphene with graphene-like materials (MoS2) for its novel properties.

Graphical abstract

Dual signaling of azide ions by deprotection of a dichlorofluorescein chloroacetate

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Jung Woo Lee , Ho Won Kim , Hyun Gyu Im , Hong Yeong Kim , Suk-Kyu Chang
We investigated the dual optical signaling of azide ions by the selective cleavage of fluorescein acetates. The chloroacetate derivative of 2′,7′-dichlorofluorescein showed prominent colorimetric and fluorogenic signaling behaviors toward azide ions in aqueous acetonitrile solution. Fluorescein analogs also showed a selective response, but the signaling speed was unfavorably slow. The detection of azide ions was not affected by the presence of commonly encountered anions. In particular, significant interference from sulfide ions in the azide-selective signaling of the probe was readily suppressed by using a Hg(II)–N,N,N′,N′-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) complex as a masking agent. The detection limit for the determination of azide ions by the chloroacetate of 2′,7′-dichlorofluorescein in 10% aqueous acetonitrile was 4.0×10⁻⁷ M (17ppb). The signaling of azide ions in real samples using tap water and simulated wastewater was also tested.

Graphical abstract

Characterization of a new fluorescence-enhancing substrate for microarrays with femtomolar sensitivity

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Marina Cretich , Clelia Galati , Lucio Renna , Guglielmo Guido Condorelli , Paola Gagni , Marcella Chiari
The demand for high sensitivity in microarray technology has stimulated the research of new labeling strategies, new substrates with increased loading capacity and new approaches to amplify the fluorescence signals. Although these methods improve the sensitivity, they are based on non-routine procedures which limit their widespread usage. A simple way to achieve fluorescence enhancement is the optical interference (OI) coating technology based on the use of substrates with films of well-defined thickness that maximize photoabsorption of the dye molecules in the vicinity of the surface and reflect the emitted light toward the detector. Here we introduce a new substrate for fluorescence enhancement composed of a thin aluminum mirror and a single quarter wave silicon oxide as a dielectric layer. The use of such material allows the development of a substrate suited for parallel production in conventional IC (Integrated Circuit's) technology, which produces a 20-fold enhancement of fluorescence compared to glass, which is the most common material used in microarrays. The new substrate was coated with a copolymer of N,N-dimethylacrylamide, N-acryloyloxysuccinimide, and 3-(trimethoxysilyl)propyl methacrylate, copoly(DMA-NAS-MAPS), which forms, by a simple and robust procedure, a functional nanometric film that covalently binds bio-probes on the surface and efficiently suppresses non-specific adsorption. The performance of the new fluorescence-enhancing substrate in microarray technology was demonstrated for the detection of a panel of inflammation biomarkers pushing detection limits into the femtomolar range.

Measurement of the evolution of rigid and viscoelastic mass contributions from fibrin network formation during plasma coagulation using quartz crystal microbalance

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Ramji S. Lakshmanan , Vitaly Efremov , Sinéad M. Cullen , Anthony J. Killard
The coagulation of blood plasma and the effect of fibrinogen concentration were studied with a quartz crystal microbalance (QCM), where frequency and half-width at half-maximum (bandwidth) values measured from the conductance spectrum near resonant frequency were used. Bandwidth change is an indicator of energy dissipation, allowing for an understanding of qualitative changes occurring during fibrin clot formation. Both frequency shift (Δf) and bandwidth shift (ΔΓ) were dependent on the concentration of fibrinogen in plasma. We defined a sum of squares function α (=Δf ²/1000+ΔΓ ²/1000) that measures absolute changes in QCM resonant characteristics to semi-quantitatively include an overall contribution of adsorbed mass and elastic modulus components and a function β (=1−ΔΓ/Δf) that indicates qualitatively the nature of response based on its deviation from ideal Newtonian behaviour. Increasing concentration of fibrinogen resulted in an increase in the value of α, showing that a larger amount of fibrinogen results in larger amount of coupled viscoelastic mass. Changes in β indicated that the nature of changes occurring was very similar to Newtonian and that coupling of rigid-mass dominates the overall response in the early stage of coagulation and in the later stage growing elastic mass compensates some of the response.

A novel BODIPY-based colorimetric and fluorometric dual-mode chemosensor for Hg2+ and Cu2+

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Xingxing He , Jing Zhang , Xungao Liu , Lin Dong , Di Li , Huayu Qiu , Shouchun Yin
A novel BODIPY-based colorimetric fluorescent sensor with bis[2-(phenylseleno)ethyl]amine as binding site (Se-1) for Hg²⁺ and Cu²⁺ has been developed. Se-1 shows high selectivity and sensitivity toward Hg²⁺ and Cu²⁺ over alkali and transition metal ions. Se-1shows a significant red-shift in the absorption spectra from 525 to 571nm for Hg²⁺ and 590nm for Cu²⁺, which induces color changes from pink to purple and blue. Upon excitation at 570nm, Se-1 upon interaction with Hg²⁺ ions displays a 5-fold fluorescence enhancement with a 2nm blue-shift, while Se-1 with Cu²⁺ exhibits a 13-fold fluorescence enhancement and red-shifts from 595 to 610nm. The binding mode of Se-1 with Hg²⁺ or Cu²⁺ has been investigated by Job's plot, ESI and ¹H NMR experiments. The absorption and fluorescence of the Se-1–Hg²⁺ complex can be reversibly restored to that of the uncomplexed ligand by using EDTA or cysteine, however, the sensing processing of Se-1 in response to Cu²⁺ ions cannot.

A microfluidic device for the hydrodynamic immobilisation of living fission yeast cells for super-resolution imaging

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Laurence Bell , Ashwin Seshia , David Lando , Ernest Laue , Matthieu Palayret , Steven F. Lee , David Klenerman
We describe a microfluidic device designed specifically for the reversible immobilisation of Schizosaccharomyces pombe (Fission Yeast) cells to facilitate live cell super-resolution microscopy. Photo-Activation Localisation Microscopy (PALM) is used to create detailed super-resolution images within living cells with a modal accuracy of >25nm in the lateral dimensions. The novel flow design captures and holds cells in a well-defined array with minimal effect on the normal growth kinetics. Cells are held over several hours and can continue to grow and divide within the device during fluorescence imaging.

Synthesis of Ag-MoS2/chitosan nanocomposite and its application for catalytic oxidation of tryptophan

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Xiaohong Xia , Zhixiang Zheng , Yan Zhang , Xiaojuan Zhao , Chunming Wang
A convenient and low-cost synthesis approach is proposed for the development of a simple and novel electrochemical sensor for the determination of tryptophan (Try). In this synthesis process, graphene-like molybdenum sulfide was successfully obtained, and silver nanoflakes (AgNFs) were directly synthesized on the surface of molybdenum sulfide (MoS2) films, in this process chitosan (CS) and ascorbic acid (AA) acted as the stabilizer and reducing agent, respectively. This nanocomposite was characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were employed to evaluate the electrochemical property of Ag-MoS2/CS toward the oxidation of tryptophan. Under the optimized experimental conditions, the oxidation peak currents are proportional to the concentrations of tryptophan over the range of 0.5μM to 120μM, and the detection limit is 0.05μM (S/N=3). Moreover, the proposed method is free of interference from other amino acid to other coexisting species.

Polymeric optodes based on upconverting nanorods for fluorescence measurements of Pb2+ in complex samples

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Jing Wu , Yu Qin
We reported here a lead ion selective optode incorporating NaYF4: Er,Yb upconverting nanorods, chromoionophore ETH 5418, and lead ionophore together in hydrophobic polymer matrixes. The absorption spectra of protonated and unprotonated ETH 5418 overlap the two emission peaks of the upconverting material, respectively, which allows the fluorescent ion sensing based on the inner filter effect. The proposed optodes exhibited highly selective and reproducible sensing property for measuring lead ions in the range of 10⁻⁶–10⁻² M at pH 5. Because the excitation source is 980nm and the emission wavelength lies in the near-infrared region, the sensors have been successfully used in complex samples for example plasma with minimized background absorption and sample autofluorescence. The lead levels in sheep plasma and artificial industry wastewater samples obtained by the optode were comparable with the known addition amounts of Pb(NO3)2, providing a new method for testing Pb²⁺ in the industry wastewater.

GADH screen-printed biosensor for gluconic acid determination in wine samples

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Lorena del Torno-de Román , M. Asunción Alonso-Lomillo , Olga Domínguez-Renedo , Arrate Jaureguibeitia , M. Julia Arcos-Martínez
Gluconate dehydrogenase (GADH) biosensors have been developed for the satisfactory determination of gluconic acid in wine samples, without any pretreatment. The biosensors have been fabricated by cross-linking immobilization of GADH onto screen-printed carbon electrodes, containing the mediator tetrathiafulvalene (TTF). Chronoamperograms have been registered at +100mV vs. screen-printed Ag/AgCl electrode by successive additions of a gluconic acid solution in the concentration range from 9.0 to 131.4μM. This method shows a reproducibility of 8.1% (n =3) related to the slopes of these calibration curves and a repeatability of 3.2% (n =5). The procedure has shown an average capability of detection of 9.0μM for a probability of false positive and negative of 0.05. Wine samples have been analyzed with these biosensors, obtaining satisfactory results.

Volume-doped cobalt titanates for ethanol sensing: An impedance and X-ray absorption spectroscopy study

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Clemens J. Belle , Günter E. Wesch , Stefan Neumeier , M. Janeth Lozano-Rodríguez , Andreas C. Scheinost , Ulrich Simon
The dynamic C2H5OH sensitivity of ilmenite-type cobalt titanates volume-doped by 2at% Li, Na, K, Sb, La, Sm, Gd, Ho and Pb was systematically studied with respect to exhaust monitoring. Therefore, the p-type semiconducting CoTiO3 materials were characterized as resistive gas sensors via high-throughput impedance spectroscopy toward 5–200ppm C2H5OH at 300–500°C. The best performing materials were tested further by time-resolved and long-term measurements whereby the CoTiO3 volume-doped with K exhibited an outstanding overall performance. X-ray absorption spectroscopy on this particular material gave evidence that the local structure around Co and Ti remains unaffected by the doping despite of a slight increase in static disorder. Hence, the effect of K doping does not originate from alteration in the metal-to-oxygen interaction as expected from previous findings.

Validation of wavelength modulation spectroscopy techniques for oxygen concentration measurement

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): S. Neethu , R. Verma , S.S. Kamble , J.K. Radhakrishnan , P.P. Krishnapur , V.C. Padaki
Tunable Diode Laser Absorption Spectroscopy (TDLAS) based gas sensing technology, has widespread applications, ranging from use in biomedical industry to aerospace applications. An experimental set-up was established to measure concentration of oxygen gas in the range 0–100% using TDLAS technique. The oxygen absorption at 760.241nm was scanned with a tunable DFB laser, and wavelength modulation spectroscopy was used to obtain the harmonics (1f, 2f, 3f & 4f) of the oxygen absorption signal. The modulation parameters such as the modulation voltage, modulation frequency, reference phase, time constant of lock in amplifier, the tuning voltage, and the tuning frequency were optimized to obtain the harmonics of high amplitude and narrow half width. Keeping the experimental parameters constant, the oxygen concentration measurements were obtained by the following three methodologies, viz, (i) using only the 2nd harmonic, (ii) using the 2nd and 4th harmonics and, (iii) using the 1st and 2nd harmonics. The results of these measurements were compared and the merits and drawbacks of these methods are discussed.

Colorimetric determination of DNA concentration and mismatches using hybridization-mediated growth of gold nanoparticle probes

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Wei-Feng Fang , Wen-Jone Chen , Jing-Tang Yang
A novel colorimetric approach to sense DNA samples was demonstrated successfully based on a concept of hybridization-mediated growth of gold nanoparticles probes (AuNP probes). The growth size and conformation of the probes are dominated by DNA samples that hybridize with the probes. The growth probes serve as nanoparticle biosensors that can be utilized to analyze concentrations of DNA samples or to discriminate mismatches of DNA samples to the probes (complementarity of DNA) in terms of size- and shape-dependence optical properties. By means of the proposed method, not only the semi-quantitation of target DNA but also the differentiation of DNA mismatches can be readily achieved with a naked eye or simple spectrophotometer. This method features small consumption of reagents, a satisfactory detection limit (about 60nM), a small duration of assay (a couple of minutes), and a simple procedure without thermal control. 

Improving Overall Growth & Performance of Primary Neurons

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AMSBIO is a leading provider of innovative products and services to support all stages of stem cell and neurobiology research from source to storage. Regardless of the application, AMSBIO offers products and services to accelerate basic, translational and clinical research.  For further information on GS21 neural supplement please visit  http://www.amsbio.com/B-27.aspx or contact AMSBIO now on +44-1235-828200 / +1-949-768-8365 or email info@amsbio.com.

Founded in 1987, AMS Biotechnology (AMSBIO) is recognized today as a leading company contributing to the acceleration of discovery through the provision of cutting-edge life science technology products and services for research and development in the medical, nutrition, cosmetics and energy industries. The AMSBIO range includes specialist antibodies, peptides and recombinant proteins. In addition the company is able to draw upon in-depth expertise in extracellular matrices to provide elegant solutions for studying cell motility, migration, invasion and proliferation. Widely acknowledged as experts in cell culture, AMSBIO partners with clients in tailoring cell systems to enhance screening outcomes and eventual prognosis. With a range of molecular detection reagents, and a significant Biorepository the company can also provide tissue DNA, RNA, protein and microarray products. Key research areas for these products include: Oncology, Regenerative Medicine, Environmental Analysis, Cytotoxicity Screening, Glycomics and Stem Cell Biology.

Hold the front page!

A paper entitled, Determination of selected biogenic amines in Acacia rigidulaplant materials and dietary supplements using LC–MS/MS methods published in the Journal of Pharmaceutical & Biomedical Analysis has made the front page of national newspaper, USA Today (see this link http://www.usatoday.com/story/news/nation/2013/11/18/fda-scientists-find-amphetamine-like-compound-in-dietary-supplements/3627963/).

The paper was published in Volume 88, 25 January 2014, Pages 457–466 and can be found here:

http://www.sciencedirect.com/science/article/pii/S0731708513004378

Just Published: Sensors & Actuators A: Physical

A new issue of this journal has just been published. To see abstracts of the papers it contains (with links through to the full papers) click here:

Sensors & Actuators A: Physical
http://rss.sciencedirect.com/publication/science/5282

Selected papers from the latest issue:

Self-writing smart labels for humidity monitoring

19 November 2013, 09:42:19

Publication date: 1 January 2014
Source:Sensors and Actuators A: Physical, Volume 205
Author(s): Christian Schoo , Meinhard Knoll
Lateral anodic oxidation is a recent display technique with potential usage in self-writing smart labels and switching applications, which have the ability to operate with established RFID units. This process requires water to operate, which is harvested by a hygroscopic electrolyte layer from the ambient atmosphere. This precondition enables the realization of a humidity monitoring functionality. We develop smart labels displaying the maximum relative humidity during a period of time by the usage of halides providing different hygroscopicity in the electrolyte layer. Therefore we investigate the behavior of the humidity monitoring smart labels under test conditions with diverse relative humidity.

Color sensing ability of an amorphous silicon position sensitive detector array system

19 November 2013, 09:42:19

Publication date: 1 January 2014
Source:Sensors and Actuators A: Physical, Volume 205
Author(s): Javier Contreras , Rodrigo Martins , Pawel Wojcik , Sergej Filonovich , Hugo Aguas , Luis Gomes , Elvira Fortunato , Isabel Ferreira
The color sensing ability of a data acquisition prototype system integrating a 32 linear array of 1D amorphous silicon position sensitive detectors (PSD) was analyzed. Besides being used to reproduce a 3D profile of highly reflective surfaces, here we show that it can also differentiate primary red, green, blue (RGB) and derived colors. This was realized by using an incident beam with a RGB color combination and adequate integration times taking into account that a color surface mostly reflects its corresponding color. A mean colorimetric error of 25.7 was obtained. Overall, we show that color detection is possible via the use of this sensor array system, composed by a simpler amorphous silicon pin junction.

Investigation of guided surface acoustic wave sensors by analytical modeling and perturbation analysis

19 November 2013, 09:42:19

Publication date: 1 January 2014
Source:Sensors and Actuators A: Physical, Volume 205
Author(s): Onursal Onen , Rasim Guldiken
In this paper, shear horizontal polarized guided surface acoustic wave propagation was investigated with analytical modeling and perturbation analysis for biosensing applications. The model was also verified experimentally. The analytical model was developed for multilayer systems taking viscoelasticity into consideration. Detailed parametric investigation of dispersion curves was conducted using various substrate materials and guiding layers. The effects of frequency and degree of viscoelasticity were also studied. Perturbation equations were developed with first order approximations by relating the dispersion curve slopes to sensitivity. Among the guiding layers investigated, Parylene C showed the highest sensitivity followed by gold, chrome and silicon dioxide. The perturbation investigations were also extended to protein layers for immunosensing applications. It was observed that viscous behavior resulted in slightly higher sensitivity, and protein layers showed almost identical sensitivity similar to polymers investigated (SU-8, Parylene, etc.). The optimum configuration is found to be Parylene-C guiding layer on a ST-cut quartz substrate for protein layer sensing and this configuration has 40 times the sensitivity of gold guiding layer on quartz substrate. Our results indicate that chrome and silicon dioxide have low sensitivity when used as guiding layers. Also, lithium tantalate substrate with gold and Parylene-C guiding layers results in ∼10% lower sensitivity as compared to quartz substrate.

MEMS based normally closed silicon microregulator for gas and water

19 November 2013, 09:42:19

Publication date: 1 January 2014
Source:Sensors and Actuators A: Physical, Volume 205
Author(s): B. Pramanick , S. Das , T.K. Bhattacharyya
This paper presents the design, fabrication and performance evaluation of a normally closed piezoelectrically actuated silicon microregulator. The microregulator is realized using two wafers process and is designed for the maximum operating pressure 5bar and it is found to be leak proof (1×10⁻⁴ sccm of helium gas).This paper also reports the development of precision fixturing, assembling and testing of the valve. One of the potential areas for application of microregulators is in satellite propulsion using ion thrusters. Ion thrusters require feed systems with very precise propellant gas flow rate and it makes microregulator a suitable candidate. Another application of the microregulator is liquid propellant flow control in micropropulsion. The water flow measurement of the same microregulator is discussed here. The hysteresis measurement of the silicon membrane using inductive probe and the cyclic test of the microregulator are also described here.

A novel compliant micropositioning stage with dual ranges and resolutions

19 November 2013, 09:42:19

Publication date: 1 January 2014
Source:Sensors and Actuators A: Physical, Volume 205
Author(s): Qingsong Xu
Dual-range stages are demanded in precision positioning applications that call for fine resolution in a smaller motion range and coarse resolution in a larger range. Traditional dual-range stages are realized using two actuators, which complicates the mechanism and control design procedures. This paper presents the design and testing of a novel dual-range, dual-resolution precision positioning stage driven by a single linear actuator. The stage structure is devised with leaf flexures to achieve a large stroke. Strain sensors are employed to provide different resolutions in the two motion ranges. To quantify the design of the motion ranges and fine/coarse resolution ratio, analytical models are established and verified through finite element analysis simulations. A proof-of-concept prototype is fabricated for experimental investigations and the experimental results validate the effectiveness of the proposed design. The reported ideas can also be extended to the design of multi-axis micropositioning stages.

Design and analysis of a 2D broadband vibration energy harvester for wireless sensors

19 November 2013, 09:42:19

Publication date: 1 January 2014
Source:Sensors and Actuators A: Physical, Volume 205
Author(s): Jin Yang , Xihai Yue , Yumei Wen , Ping Li , Qiangmo Yu , Xiaoling Bai
This paper presents a design for a novel vibration energy harvester using a magnetoelectric (ME) transducer, which is efficiently applicable in two-dimensional (2D) motion and over a range of vibration frequencies. This harvester adopts a circular cross-section cantilever rod to extract the ambient vibration energy because of its ability to host accelerations in arbitrary motion directions. Moreover, the magnetic interactions between the magnets and the ME transducer will lead to the nonlinear oscillation of the rod with increased frequency bandwidth. The influences of the nonlinear vibration factor and magnetic field distribution on the electrical output and bandwidth of the harvester are investigated to achieve optimal vibration energy harvesting performances. The experimental results showed that, the harvester was sensitive to the vibration with arbitrary in-plane directions. With an acceleration of 0.6g (where g =9.8ms⁻²), it had the working bandwidths of 4.2Hz, 2.6Hz, 2.3Hz, 2.5Hz and 3.2Hz, and the output powers of 0.6mW, 0.49mW, 0.33mW, 0.5mW and 0.56mW at the in-plane excitation angles of−90°, −45°, 0°, 45° and 90°, respectively.

Design and evaluation of a skin-like sensor with high stretchability for contact pressure measurement

19 November 2013, 09:42:19

Publication date: 15 December 2013
Source:Sensors and Actuators A: Physical, Volume 204
Author(s): Debao Zhou , Haopeng Wang
This paper presents the development of a new type of skin-like tactile pressure sensor array. The sensor array is scalable, flexible and stretchable and can measure pressure up to 250kPa within 30% stretching rate without damaging its mechanical structure. It can also conform to irregular three-dimensional surfaces. The sensor array consists of three layers. The top and bottom layers are formed by the array of parallel conductive strips made of silver nanowires (AgNWs) embedded in polydimethylsiloxane (PDMS) thin films. The AgNWs/PDMS conductor strips are used as stretchable interconnections to transmit electrical signals. The middle layer is made of PDMS. This film is pre-molded with holes filling with cylinder-shaped conductive elastomer for pressure measurement. In this paper, the characteristic of the AgNWs/PDMS conductor strips as stretchable interconnections is studied. The piezoresistive properties of the sensels (one sensing element is called a sensel) were measured and discussed. The performance of the tactile sensor array under stretching was also tested. With the associated scanning power-supply circuit and data acquisition system, it is demonstrated that the system can successfully capture the tactile images induced by objects of different shapes. Such sensor system could be applied on curved or non-planar surfaces in robots or medical devices for force detection and feedback.

Improvement of the off-diagonal magnetoimpedance sensor white noise

19 November 2013, 09:42:19

Publication date: 15 December 2013
Source:Sensors and Actuators A: Physical, Volume 204
Author(s): M. Malatek , B. Dufay , S. Saez , C. Dolabdjian
This work deals with the analysis of noise sources of the off-diagonal magneto-impedance sensor with stress-annealed amorphous ribbon. This experimental analysis shows that the equivalent magnetic noise spectral density is mostly due to the electronic conditioning circuitry that operates the sensor. The electronic noise was then reduced with employment of an improved excitation-detection technique for our sensor and an equivalent magnetic noise spectral density below 1 pT / Hz in white noise region has been reached. Indeed, the equivalent magnetic white noise level of the output signal decreased from 5 pT / Hz to 560 fT / Hz . Nevertheless, this noise level is still limited by the electronic conditioning, leaving room for further improvement.

Laser-unzipped carbon nanotube based glucose sensor for separated structure of enzyme modified field effect transistor

19 November 2013, 09:42:19

Publication date: 15 December 2013
Source:Sensors and Actuators A: Physical, Volume 204
Author(s): Wan-Lin Tsai , Yun-Shan Chien , Po-Yu Yang , I-Che Lee , Kuang-Yu Wang , Huang-Chung Cheng
A glucose sensing film composed of unzipped multiwalled carbon nanotubes (MWCNTs) via continuous-wave laser irradiation is investigated. Some structural defects decorate on MWCNTs after an acid treatment, and the MWCNTs are unzipped into sheet-shaped layers initiated from these defects after the laser irradiation. The laser-irradiated carbon nanotube thin films (CNTFs) possess higher conductance owing to larger contact area, and the side edges of unzipped CNTs could act as sensing sites for hydrogen ions. Thus the laser-irradiated CNTF as a glucose sensing film could achieve a higher sensitivity of 0.302mV(mg/dl)⁻¹, equal to 7.55mV(mg/dl)⁻¹ per centimeter square, and a larger linearity of 0.9947 than the as-sprayed one. Moreover, the fully low-temperature processes of this work also reveal the potentials for flexible and disposable biosensors.

Highly enhanced piezoelectric properties of PLZT/PVDF composite by tailoring the ceramic Curie temperature, particle size and volume fraction

19 November 2013, 09:42:19

Publication date: 15 December 2013
Source:Sensors and Actuators A: Physical, Volume 204
Author(s): Peng Han , Shengli Pang , Jingbo Fan , Xiangqian Shen , Tiezheng Pan
Piezoelectric oxides Pb1−x La x (Zr y Ti1−y )1−x/4O3 (PLZT) were synthesized by the solid-state reaction process and Pb0.96La0.04(Zr0.54Ti0.46)0.99O3/polyvinylidene fluoride (PL0.04ZT/PVDF), Pb0.92La0.07(Zr0.555Ti0.445)0.9825O3/PVDF (PL0.07ZT/PVDF) composites with various particle sizes and contents (50–90vol.%) of the ceramic phase were prepared by the hot-press process. The Curie temperature (T c ) of PLZT decreases monotonously from 312°C to 98°C with La content (x) increasing from 0.02 to 0.09. The polarizability of PLZT/PVDF composites increases from 39.5% (PL0.04ZT/PVDF) to 56.7% (PL0.07ZT/PVDF) when poled at 125°C (at the vicinity of T c of PL0.07ZT). As a result, the electrical property improvement with d 33 (ɛ r ) from 53pC/N (159) to 76pC/N (222) proves that tailoring T c of the piezoelectric ceramic to the poling temperature is a useful way to enhance the piezoelectric and dielectric properties of the ceramic/polymer composite. To further investigate the electrical properties of the 0–3 type PLZT/PVDF composite, the particle size and volume fraction of PLZT are also optimized.

Nanometer scale active ground motion isolator

19 November 2013, 09:42:19

Publication date: 15 December 2013
Source:Sensors and Actuators A: Physical, Volume 204
Author(s): R. Le Breton , G. Deleglise , J. Allibe , A. Badel , G. Balik , B. Caron , A. Jeremie , J. Lottin , S. Vilalte
Vibration isolation is a critical issue in various precision engineering fields. A new design of an active isolation system operating heavy loads (up to 50kg) is presented in this work. This system provides state of the art vibration isolation at the nanometer scale for magnets of a future particle accelerator and is more compact than other studies in this field. The choice of sensors and actuators, the mechanical design and the acquisition electronics are investigated in order to reject ground motion efficiently. A dynamic experimental characterization is performed. Based on the identified model, a specific controller, giving an attenuation between 10Hz and 100Hz was designed and experimentally qualified.

Development of an auto-calibrated interfacing circuit for thick film multi-gas sensor

19 November 2013, 09:42:19

Publication date: 15 December 2013
Source:Sensors and Actuators A: Physical, Volume 204
Author(s): R. Khakpour , M.N. Hamidon , G.A.E. Vandenbosch
A simple, cheap, and integrated architecture is introduced to measure gases with a thick film gas sensor. The temperatures of the sensors are stabilized by controlling the heaters of the sensors. The heaters’ temperatures are measured by sampling the heaters resistance through the use of a voltage divider and ADCs. A microcontroller accordingly adjusts the output of DACs in order to apply the appropriate steering voltage to the heaters. The method employed to measure the gases is to sample the voltage drop over the resistances of the sensors, which are depending on the gases, by ADCs. The innovation lies in the simplicity of the design and the use of different simple methods and commercially available technologies to fabricate the circuit. Also, a single microcontroller is used to drive and control the heaters’ temperature, to compensate ambient temperature of the heaters, to measure and monitor the amount of gases detected by sensors and finally, to select the sensors. This opens the possibility to use these gas sensors for monitoring purposes at a large scale, for example in alarms and computers.

Development of piezoelectric coaxial filament sensors P(VDF-TrFE)/copper for textile structure instrumentation

19 November 2013, 09:42:19

Publication date: 15 December 2013
Source:Sensors and Actuators A: Physical, Volume 204
Author(s): M.B. Kechiche , F. Bauer , O. Harzallah , J.-Y. Drean
Coaxial filaments based on Poly (vinylidene fluoride-co-trifluoroethylene) and copper filament was developed, their mechanical properties characterized. They were then instrumented in textile structure and their detection capabilities were observed. P(VDF-TrFE)/copper coaxial filaments were obtained by a melt spinning process, the mechanical drawing applied at the end of spinning process enabled the increasing of the crystalline β phase from 43% for the copolymer in pellet shape to 52% for the developed coaxial filament of 250μm in diameter. Coaxial filaments surfaces and sections have been analyzed with a scanning electron microscope. The mechanical properties have been quantified by tensile analyses. Coaxial filaments were polarized by the ISL process in order to correlate the level of the polarization with the piezoelectric activity. The textile instrumentation was tested by the integration of some samples in the weft direction of a weaving structure using an industrial weaving machine (Muller NCE 10). An example of electrical signal delivered by integrated filament in textile when subjected to strain and stress actions is shown.

A multi-frequency vibration-based MEMS electromagnetic energy harvesting device

19 November 2013, 09:42:19

Publication date: 15 December 2013
Source:Sensors and Actuators A: Physical, Volume 204
Author(s): Huicong Liu , You Qian , Chengkuo Lee
A multi-frequency vibration-based MEMS electromagnetic energy harvesting (EH) device has been presented, fabricated and characterized in this paper. It consists of a permanent magnet and a circular suspension structure on a MEMS EH chip. By emulating the magnetic field of a cylinder magnet, the gap distance between the magnet and EH chip is optimized to be zero for achieving larger magnetic flux change and higher output performance. From the experimental results, the vibration energy can be harvested at three excitation frequencies of 840, 1070 and 1490Hz, which corresponds to the out-of-plane (mode I), torsion (mode II/III) and in-plane (mode IV/V) vibrations of the EH device, respectively. The maximum power densities at these three frequencies are 0.157, 0.014 and 0.117μW/cm³, respectively, for a matched load resistance of 626Ω and an input acceleration of 1.0g. The feasibility study results show promising application potentials for harvesting energy from vibrations of multi-frequency.  

Starter Kit for SPE Sample Preparation

Porvair Sciences has announced the Microlute SPE sample preparation starter kit.

This kit contains everything needed to begin productive SPE sample preparation in a 96 well plate format, including two development filter plates and a popular C18 sorbent filter plate, 2ml collection plates, disposable waste trays and, most importantly, the Microlute Acrylic Vacuum Manifold.

The new starter kit offers all the advantages of SPE sample preparation in a convenient microplate format, capable of rapidly processing 96 samples in one run, repeatedly and precisely. All that is required for full operation is a suitable laboratory vacuum connection or pump.

Handling samples as small as 150µl - the Microlute™ SPE starter kit helps to increase analytical sensitivity by providing pre-injection clean-up and concentration. Two ‘Development Microlute’ plates in the kit are pre-loaded with eight different sorbents to aid method development. Once the most suitable sorbent has been identified, whole plates containing the chosen material can be ordered for use with the Microlute system. Standard 2ml sample collection plates are supplied, but dedicated plates with well volumes of 350 ul and 1ml may also be used to optimally match your sample preparation requirements. The supplied disposable polycarbonate waste trays simplify waste solvent handling during sample clean up.

Constructed from a single piece of moulded ultra-pure polypropylene, the Microlute™ plate will not bend or distort, unlike individual SPE cartridges which have to be repeatedly plugged in and out. Using a proprietary technique, Porvair has eliminated the channelling effects that often limit the performance of SPE columns. Each well on a Microlute™ plate has an individual drain spout ensuring 100% sample transfer and zero crossover contamination. To recover dried or concentrated sample the Microlute™ SPE sample preparation starter kit may be coupled to a Porvair MiniVap sample concentrator.

For further information please visit www.porvair-sciences.com/en/services-menu/solid-phase-extraction/spe-starter-pack/ or contact Porvair Sciences on +44-1978-666240 /  int.sales@porvair-sciences.com.