Biosensors

Bio-hybrid tactile sensor and experimental set-up for investigating and mimicking the human sense of touch

by David Cheneler

Cheneler, D., Buselli, E, Oddo, C. M., Kaklamani, G., Beccai, L, Carrozza, M. C., Grover, L., Anthony, C., Ward, M. C. L. and Adams, M., (2012), Bio-hybrid tactile sensor and experimental set-up for investigating and mimicking the human sense of touch, Proceedings of HRI2012, Boston, USA, 3rd March 2012

In this paper, we describe the design and fabrication of a bio-hybrid tactile sensor and experimental platform. The... more In this paper, we describe the design and fabrication of a bio-hybrid tactile sensor and experimental platform. The system uses tissue engineered alginate encapsulated fibroblasts and a conductivity sensor as a transduction system to monitor applied normal and tangential loads in a manner comparable to mechanotransduction in the human haptic system in nonglabrous skin. The tissue is integrated into a microfluidic system interfaced with a nanoporous membrane capable of sustaining the viability of the cells for extended times. The efficacy of the bio-hybrid tactile sensor is validated using a 2 DoF Cartesian manipulator, capable of indenting and sliding textured stimuli over the device. Also, the platform includes a two-cell Peltier-based temperature controlled control module. This allows the evaluation of the effect of temperature variation on the bio-hybrid sensor response, and to decouple the effect of temperature from mechanical stimulation.

Recent advances in biosensory and medicinal therapeutic applications of zinc (II) and copper (II) coordination complexes

by Joel Drewry

Label-free detection of Staphylococcus aureus in skin using real-time potentiometric biosensors based on carbon nanotubes and aptamers

by Gustavo Zelada-Guillen

Published in 'Biosensors & Bioelectronics', 2011

In this paper we report the first biosensor that is able to detect Staphylococcus aureus in real-time. A network of... more In this paper we report the first biosensor that is able to detect Staphylococcus aureus in real-time. A network of single-walled carbon nanotubes (SWCNTs) acts as an ion-to-electron potentiometric transducer and anti-S. aureus aptamers are the recognition element. Carbon nanotubes were functionalized with aptamers using two different approaches: (1) non-covalent adsorption of drop-casted pyrenil-modified aptamers onto the external walls of the SWCNTs; and (2) covalent bond formation between amine-modified aptamers and carboxylic groups previously introduced by oxidation at the ends of the SWCNTs. Both of these approaches yielded functional biosensors but there were large differences in the minimum detectable bacteria concentration and sensitivity values. With covalent functionalization, the minimum concentration detected was 8 × 102 colony-forming units (CFU)/mL and the sensitivity was 0.36 mV/Decade. With the non-covalent approach, the sensitivity was higher (1.52 mV/Decade) but the minimum concentration detected was greatly affected (107 CFU/mL). In both cases, potential as a function of Decade of bacteria concentration was linear. Functional biosensors were used to test real samples from freshly excised pig skin, contaminated with the target microorganism, as a surrogate for human skin.

Densities and orientations of antibodies on nano-textured silicon surfaces

by RamChander Ch

Dynamic Separation of Magnetic Nanoparticles In a Microfluidic System with Different Flow Conditions

by Johann F. Osma

Juan R. Reyes1, Diego F. Cuervo2, Angel A. Galvis3, Johann F. Osma4 and Watson L. Vargas1, (1)Department of Chemical Engineering, Universidad de los Andes, Bogota, D.C, Colombia, (2)CMUA. Department of Electrical and Electronics Engineering, Universidad de los Andes, Bogota, D.C, Colombia, (3)Chemical Engineering, Universidad de los Andes, Bogota, D.C, Colombia, (4)CMUA. Department of Electrical and Electronics Engineering,, Universidad de los Andes, Bogota, D.C, Colombia

Controlled magnetic-field based separation of molecules in microfluidics systems has been the focus of attention... more
Controlled magnetic-field based separation of molecules in microfluidics systems has been the focus of attention in recent years due to their vast applications in immunological assays, disease diagnosis and biomedical research. Therefore, studies on the development of numerical models and their comparison with experiments of controllable separation of magnetic nanoparticles in microfluidics systems are of great interest and are actively been pursued. In this work, both experimental and computational results on the separation of magnetic particles are discussed.

The experimental part of this work involves the synthesis of nanoparticles, the fabrication of microsystems and the analysis of the system under the influence of magnetic fields with different flow conditions. The nanoparticles used in this study are particles of magnetite, synthesized by the coprecipitation method. Naked Fe2O3-Fe3O nanoparticles were covered with a thin shell of silica using the well-known method developed by Stöber in order to study core-shell nanoparticles in the microfluidics system.  The silica-modified (hematite-magnetite) nanoparticles were then functionalized with a silane monolayer. Finally due to the importance of gold surface in biological funtionalization, core-shell nanoparticles of Fe3O4@SiO2@Au were used in this work. The nanoparticles samples are characterized by X-ray diffraction (XRD), Dynamic Light Scattering (DLA), Zeta potential, Scanning Electron microscopy (SEM), Transmission electron microscopy (TEM), and Magnetic susceptibility.

In the computational section of this work, we have simulated the magnetic-field based separation of the nanoparticles using a multi-physics finite-element method to predict the motion and capture of the magnetic nanoparticles as a first approximation. We also have simulated the system as a discrete mixture of magnetic nanoparticles in a continuos media. The simulations have been done in two different geometries and with different flow conditions. The position and angle of the magnet have also been examined.

The simulation and experimental results are compared in order to analyze the distribution and the efficiency of the separation of the magnetic core-shell nanoparticles. The results show that the models developed in this study could be useful in assisting the design of magnetic-field based separation Microsystems with potential applications on medical diagnosis.

A Pd framework for the Xth Sense: enabling computers to sense human kinetic behaviour

by Marco Donnarumma

Published in Proceedings of the 4th Pure Data Convention (PdCon), Weimar, 2011.

The Xth Sense is an interactive system for the biophysical generation and control of music. It makes use of muscle... more The Xth Sense is an interactive system for the biophysical generation and control of music. It makes use of muscle sounds produced by a performer as both raw sonic material and control data. Presently the Xth Sense (XS) technology consists of low-cost, wearable biosensors and a Pure Data based application for capture, analysis, real time processing and playback of human muscle sounds. The technical implementation of the XS biosensors has been recently illustrated in [2].
This paper describes the design of the XS software; it is a program that enables a computer to “listen” to the MMG signals transduced by the XS biosensors, to understand the performance main features, and therefore to interact with the performer. After a brief introduction on the nature of the interaction fostered by the XS technology, I focus on the framework main features such as: the XS library, a tabbed dynamic interface (TDI), a MMG features extraction unit, and a graph-on-parent3 (GOP) routing system for dynamic
mapping of gesture to sound.


[2] Donnarumma, M., “Xth Sense: researching muscle sounds for an experimental paradigm of musical performance” in Proceedings of the Linux Audio Conference (LAC), Maynooth, 2011.

Modeling the Electrostatic Signature of Single Enzyme Activity

by Landon Prisbrey

J. Phys. Chem. B, 114 3330-3333 (2010)
http://dx.doi.org/10.1021/jp910946v

Charge sensors based on nanoscale field-effect transistors are a promising new tool to probe the dynamics of... more Charge sensors based on nanoscale field-effect transistors are a promising new tool to probe the dynamics of individual enzymes. However, it is currently unknown whether the electrostatic signals associated with biological activity exceed detection limits. We report calculations of electrostatic signatures of two representative enzymes, deoxyribonuclease I and T4 lysozyme. Our simulations reveal that substrate binding to deoxyribonuclease and internal dynamics of lysozyme are detectable at the single-molecule level using existing point-functionalized carbon nanotube sensors.

Approaching intelligent infection diagnostics: Carbon fibre sensor for electrochemical pyocyanin detection

by Stephen Forsythe

Human Immunoglobulin Adsorption Investigated by Means of Quartz Crystal Microbalance Dissipation, Atomic Force Microscopy, Surface Acoustic Wave, and Surface …

by Laurent Francis

Thin film acoustic waveguides and resonators for gravimetric sensing applications in liquid

by Laurent Francis

Influence of electromagnetic interferences on the mass sensitivity of Love mode surface acoustic wave sensors

by Laurent Francis

Surface acoustic waveguides have found an application for (bio)chemical detection. The mass modification due to... more Surface acoustic waveguides have found an application for (bio)chemical detection. The mass modification due to surface adsorption leads to measurable changes in the propagation properties of the waveguide. Among a wide variety of waveguides, the Love mode device has been investigated because of its high mass sensitivity. The acoustic signal launched and detected in the waveguide by electrical transducers is accompanied by an electromagnetic wave; the interaction of the two signals, easily enhanced by the open structure of the sensor, creates interference patterns in the transfer function of the sensor. The interference peaks are used to determine the sensitivity of the acoustic device. We show that electromagnetic interferences generate a distortion in the experimental value of the sensitivity. This distortion is not identical for the two classical instrumentation of the sensor that are the open and the closed loop configurations. Our theoretical approach is completed by the experimentation of an actual Love mode sensor operated under liquid conditions and in an open loop configuration. The experiment indicates that the interaction depends on frequency and mass modifications.

A SU-8 liquid cell for surface acoustic wave biosensors

by Laurent Francis

One significant challenge facing biosensor development is packaging. For surface acoustic wave based biosensors,... more One significant challenge facing biosensor development is packaging. For surface acoustic wave based biosensors, packaging influences the general sensing performance. The acoustic wave is generated and received thanks to interdigital transducers and the separation between the transducers defines the sensing area. Liquids used in biosensing experiments lead to an attenuation of the acoustic signal while in contact with the transducers. We have developed a liquid cell based on photodefinable epoxy SU-8 that prevents the presence of liquid on the transducers, has a small disturbance effect on the propagation of the acoustic wave, does not interfere with the biochemical sensing event, and leads to an integrated sensor system with reproducible properties. The liquid cell is achieved in two steps. In a first step, the SU-8 is precisely patterned around the transducers to define 120 μm thick walls. In a second step and after the dicing of the sensors, a glass capping is placed manually and glued on top of the SU-8 walls. This design approach is an improvement compared to the more classical solution consisting of a pre-molded cell that must be pressed against the device in order to avoid leaks, with negative consequences on the reproducibility of the experimental results. We demonstrate the effectiveness of our approach by protein adsorption monitoring. The packaging materials do not interfere with the biomolecules and have a high chemical resistance. For future developments, wafer level bonding of the quartz capping onto the SU-8 walls is envisioned.

Techniques to evaluate the mass sensitivity of Love mode surface acoustic wave biosensors

by Laurent Francis

IEEE Ultrasonics, and Frequency Control Symposium - Montreal - 2004

We investigated the mass sensitivity of Love mode SAW biosensors by experimental and theoretical techniques. A first... more We investigated the mass sensitivity of Love mode SAW biosensors by experimental and theoretical techniques. A first experimental approach is based on the analysis of the dispersion curve of the sensor, which helps to determine by derivation a value of the mass sensitivity. In order to obtain the dispersion curve, we have performed a chemical wet etching procedure, which enables the continuous monitoring of the transfer function during the etching of the entire guiding layer. A second experimental approach is based on the addition and removal of layers in known quantities. The mass sensitivity is estimated in different cases: etching of a thin gold layer, copper electrodeposition, and surface adsorption of an ionic surfactant. The results obtained by these techniques are compared to a theoretical model. In the theoretical model, the layered structure of the acoustic sensor is described in terms of mechanical transmission lines and the model is used to determine the sensitivity of the acoustic device to density and viscosity variations of thin films and bulk materials. The attenuation and phase shifts are quantified and analyzed to identify the type of interaction between the adsorbed biomolecules layer and the sensor. We conclude that the Love mode SAW biosensor must be considered and optimized as a viscosity sensor and an independent layer thickness measurement is needed to apply adequately the theoretical model.

Thickness and viscosity of organic thin films probed by combined surface acoustic Love wave and surface plasmon resonance

by Laurent Francis

Proc. IEEE Ultrason. Symp. 2005

Direct detection biosensors aim at detecting molecular (antibody-antigen, DNA hybridation, cell attachment) binding... more Direct detection biosensors aim at detecting molecular (antibody-antigen, DNA hybridation, cell attachment) binding events by means of electrical, mechanical or optical effects. A quantitative analysis of the amount of material bound to the surface requires the knowledge of the physical properties of the layer, namely optical index/dielectric constant, density, thickness, and a proper model of the interaction of this layer with the probing field (acoustic or optical). We here focus on the insitu identification of the physical properties of thin organic (polymer and protein) layers bound to a substrate supporting the propagation of surface acoustic waves. In order to resolve some uncertainty on the resulting acoustic parameters, we propose the simultaneous probing of the same bound layer by optical methods (surface plasmon resonance) in a combined instrument as a means to uniquely identify the physical properties of the layer, namely the density, optical index, viscosity and thickness of the layer. We illustrate this technique for protein layers of collagen and fibrinogen. We then propose two models - transmission line and harmonic admittance computation - for analyzing these data and extract a quantitative viscosity information.

Prostate-specific antigen immunosensing based on mixed self-assembled monolayers, camel antibodies and colloidal gold enhanced sandwich assays

by Laurent Francis

Prostate-specific antigen (PSA) is a valuable biomarker for prostate cancer screening. We developed a PSA immunoassay... more Prostate-specific antigen (PSA) is a valuable biomarker for prostate cancer screening. We developed a PSA immunoassay on a commercially available surface plasmon resonance biosensor. Our PSA receptor molecule consists of a single domain antigen-binding fragment, cAbPSA-N7, derived from dromedary heavy-chain antibodies and identified after phage display. It binds PSA with a high kon value of 1.9 × 106 M−1 s−1, and was covalently immobilised on a gold substrate via a mixed self-assembled monolayer (SAM) of alkanethiols by using carbodiimide-coupling chemistry in 10 mM acetate buffer pH 5.5 to obtain an optimal pre-concentration. The best performing and optimised mixed SAM consisted of (10%) 16-mercapto-1-hexadecanoic acid (16-MHA) for covalent cAbPSA-N7 immobilisation and (90%) 11-mercapto-1-undecanol (11-MUOH) to minimise non-specific adsorption of the analyte. In this way, two advantages are incorporated in a single coupling layer. Up to 28 fmol/mm2 of cAbPSA-N7 could be immobilised and 30% of its binding sites participate actively in PSA interaction. In addition, the optimised layer showed also optimal performance to assess physiological samples. Although PSA concentrations as low as 10 ng/ml could be detected directly, this detection limit could be enhanced to PSA levels in the sub ng/ml range by introducing a sandwich assay involving a biotinylated secondary antibody and streptavidin modified gold nanoparticles. This approach realises the PSA detection at clinical relevant concentrations.

Monolithic Centrifugal Microfluidic Platform for Bacteria Capture and Concentration, Lysis, Nucleic-Acid Amplification and Real Time Detection.

by Justin O'Grady

MEMS

Development of microelectronic based biosensors

by Laurent Francis

Biosensors offer the opportunity to sense the biological world providing valuable information for medical diagnostics,... more Biosensors offer the opportunity to sense the biological world providing valuable information for medical diagnostics, analytical chemistry, environmental monitoring and fundamental research. Convergence of engineered (bio)chemical surfaces with micro- and nano- systems promises tremendous advances and potential cost reductions in biotechnology. This paper introduces some key challenges facing biosensor development, focussing on opportunities that arise from microsystem platforms utilising novel materials and processes. Examples from our work are presented illustrating the implementation of acoustic wave sensors and novel FET-type sensors.

Morphologyand laccase production of white-rot fungi grown on wheat bran flakes under semi-solid-state fermentation conditions

by Johann F. Osma

Osma, Johann F., Moilanen, Ulla, Toca-Herrera, Jose L., Rodriguez-Couto, Susana

FEMS MICROBIOLOGY LETTERS Volume: 318 Issue: 1 Pages: 27-34 Published: MAY 2011

In this paper, we studied the laccase production and the growth morphology of different white-rot fungi, i.e.... more In this paper, we studied the laccase production and the growth morphology of different white-rot fungi, i.e. Pleurotus ostreatus, Trametes pubescens, Cerrena unicolor and Trametes versicolor, cultured under semi-solid-state fermentation conditions using wheat bran flakes as a natural low-cost support substrate. Trametes versicolor exhibited the highest laccase activity per gram of total dry matter, followed by P. ostreatus (63.5 and 58.2 U g-1, respectively). In addition, they showed a time profile of laccase production that was quite similar. Growth morphology was studied using environmental microscopic images and analyzed by discrete Fourier transformation-based software to determine the mean diameter of the hyphae, the number of hypha layers and the global micromorphology. The four strains exhibited different micromorphologies of growth. Pleurotus ostreatus presented narrow hyphae, which formed many thick clumps, T. pubescens and T. versicolor showed clumps of different sizes and C. unicolor showed thick hyphae that formed larger clumps, but in less amounts.

MEMS Biosensor for Potential Cancer Cell Detection

by Anis Nurashikin Nordin

In situ evaluation of density, viscosity and thickness of adsorbed soft layers by combined surface acoustic wave and surface plasmon resonance

by Laurent Francis

We show the theoretical and experimental combination
of acoustic and optical methods for the in situ... more We show the theoretical and experimental combination
of acoustic and optical methods for the in situ quantitative
evaluation of the density, the viscosity, and the thickness
of soft layers adsorbed on chemically tailored metal
surfaces. For the highest sensitivity and an operation in
liquids, a Love mode surface acoustic wave (SAW) sensor
with a hydrophobized gold-coated sensing area is the
acoustic method, while surface plasmon resonance (SPR)
on the same gold surface as the optical method is
monitored simultaneously in a single setup for the realtime
and label-free measurement of the parameters of
adsorbed soft layers, which means for layers with a
predominant viscous behavior. A general mathematical
modeling in equivalent viscoelastic transmission lines is
presented to determine the correlation between experimental
SAW signal shifts and the waveguide structure
including the presence of the adsorbed layer and the
supporting liquid from which it segregates. A methodology
is presented to identify from SAW and SPR simulations
the parameters representatives of the soft layer. During
the absorption of a soft layer, thickness or viscosity
changes are observed in the experimental ratio of the SAW
signal attenuation to the SAW signal phase and are
correlated with the theoretical model. As application
example, the simulation method is applied to study the
thermal behavior of physisorbed PNIPAAm, a polymer
whose conformation is sensitive to temperature, under a
cycling variation of temperature between 20 and 40 °C.
Under the assumption of the bulk density and the bulk
refractive index of PNIPAAm, thickness and viscosity of
the film are obtained from simulations; the viscosity is
correlated to the solvent content of the physisorbed layer.