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725 KiB

Open AccessArticle

by Luigi Sasso, Patricia Vazquez †, Indumathi Vedarethinam, Jaime Castillo-León, Jenny Emnéus and Winnie E. Svendsen

Sensors 2010, 10(12), 10986-11000; https://doi.org/10.3390/s101210986 - 03 Dec 2010

Cited by 19 | Viewed by 10687

Abstract

Conducting polymer 3D microelectrodes have been fabricated for possible future neurological applications. A combination of micro-fabrication techniques and chemical polymerization methods has been used to create pillar electrodes in polyaniline and polypyrrole. The thin polymer films obtained showed uniformity and good adhesion to [...] Read more.

Conducting polymer 3D microelectrodes have been fabricated for possible future neurological applications. A combination of micro-fabrication techniques and chemical polymerization methods has been used to create pillar electrodes in polyaniline and polypyrrole. The thin polymer films obtained showed uniformity and good adhesion to both horizontal and vertical surfaces. Electrodes in combination with metal/conducting polymer materials have been characterized by cyclic voltammetry and the presence of the conducting polymer film has shown to increase the electrochemical activity when compared with electrodes coated with only metal. An electrochemical characterization of gold/polypyrrole electrodes showed exceptional electrochemical behavior and activity. PC12 cells were finally cultured on the investigated materials as a preliminary biocompatibility assessment. These results show that the described electrodes are possibly suitable for future in-vitro neurological measurements. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Denmark)

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917 KiB

Open AccessArticle

Fabrication and Characterization of 3D Micro- and Nanoelectrodes for Neuron Recordings

by Maria Dimaki, Patricia Vazquez, Mark Holm Olsen, Luigi Sasso, Romen Rodriguez-Trujillo, Indumathi Vedarethinam and Winnie E. Svendsen

Sensors 2010, 10(11), 10339-10355; https://doi.org/10.3390/s101110339 - 17 Nov 2010

Cited by 21 | Viewed by 9149

Abstract

In this paper we discuss the fabrication and characterization of three dimensional (3D) micro- and nanoelectrodes with the goal of using them for extra- and intracellular studies. Two different types of electrodes will be described: high aspect ratio microelectrodes for studying the communication [...] Read more.

In this paper we discuss the fabrication and characterization of three dimensional (3D) micro- and nanoelectrodes with the goal of using them for extra- and intracellular studies. Two different types of electrodes will be described: high aspect ratio microelectrodes for studying the communication between cells and ultimately for brain slice recordings and small nanoelectrodes for highly localized measurements and ultimately for intracellular studies. Electrical and electrochemical characterization of these electrodes as well as the results of PC12 cell differentiation on chip will be presented and discussed. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Denmark)

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411 KiB

Open AccessArticle

Metaphase FISH on a Chip: Miniaturized Microfluidic Device for Fluorescence in situ Hybridization

by Indumathi Vedarethinam, Pranjul Shah, Maria Dimaki, Zeynep Tumer, Niels Tommerup and Winnie E. Svendsen

Sensors 2010, 10(11), 9831-9846; https://doi.org/10.3390/s101109831 - 02 Nov 2010

Cited by 26 | Viewed by 12889

Abstract

Fluorescence in situ Hybridization (FISH) is a major cytogenetic technique for clinical genetic diagnosis of both inherited and acquired chromosomal abnormalities. Although FISH techniques have evolved and are often used together with other cytogenetic methods like CGH, PRINS and PNA-FISH, the process continues [...] Read more.

Fluorescence in situ Hybridization (FISH) is a major cytogenetic technique for clinical genetic diagnosis of both inherited and acquired chromosomal abnormalities. Although FISH techniques have evolved and are often used together with other cytogenetic methods like CGH, PRINS and PNA-FISH, the process continues to be a manual, labour intensive, expensive and time consuming technique, often taking over 3–5 days, even in dedicated labs. We have developed a novel microFISH device to perform metaphase FISH on a chip which overcomes many shortcomings of the current laboratory protocols. This work also introduces a novel splashing device for preparing metaphase spreads on a microscope glass slide, followed by a rapid adhesive tape-based bonding protocol leading to rapid fabrication of the microFISH device. The microFISH device allows for an optimized metaphase FISH protocol on a chip with over a 20-fold reduction in the reagent volume. This is the first demonstration of metaphase FISH on a microfluidic device and offers a possibility of automation and significant cost reduction of many routine diagnostic tests of genetic anomalies. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Denmark)

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1954 KiB

Open AccessArticle

Novel Designs for Application Specific MEMS Pressure Sensors

by Giulio Fragiacomo, Kasper Reck, Lasse Lorenzen and Erik V. Thomsen

Sensors 2010, 10(11), 9541-9563; https://doi.org/10.3390/s101109541 - 28 Oct 2010

Cited by 37 | Viewed by 16784

Abstract

In the framework of developing innovative microfabricated pressure sensors, we present here three designs based on different readout principles, each one tailored for a specific application. A touch mode capacitive pressure sensor with high sensitivity (14 pF/bar), low temperature dependence and high capacitive [...] Read more.

In the framework of developing innovative microfabricated pressure sensors, we present here three designs based on different readout principles, each one tailored for a specific application. A touch mode capacitive pressure sensor with high sensitivity (14 pF/bar), low temperature dependence and high capacitive output signal (more than 100 pF) is depicted. An optical pressure sensor intrinsically immune to electromagnetic interference, with large pressure range (0–350 bar) and a sensitivity of 1 pm/bar is presented. Finally, a resonating wireless pressure sensor power source free with a sensitivity of 650 KHz/mmHg is described. These sensors will be related with their applications in harsh environment, distributed systems and medical environment, respectively. For many aspects, commercially available sensors, which in vast majority are piezoresistive, are not suited for the applications proposed. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Denmark)

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1313 KiB

Open AccessArticle

Refractive Index Sensor Based on a 1D Photonic Crystal in a Microfluidic Channel

by Pedro S. Nunes, Niels Asger Mortensen, Jörg P. Kutter and Klaus B. Mogensen

Sensors 2010, 10(3), 2348-2358; https://doi.org/10.3390/s100302348 - 22 Mar 2010

Cited by 46 | Viewed by 10758

Abstract

A refractive index sensor has been fabricated in silicon oxynitride by standard UV lithography and dry etching processes. The refractive index sensor consists of a 1D photonic crystal (PhC) embedded in a microfluidic channel addressed by fiber-terminated planar waveguides. Experimental demonstrations performed with [...] Read more.

A refractive index sensor has been fabricated in silicon oxynitride by standard UV lithography and dry etching processes. The refractive index sensor consists of a 1D photonic crystal (PhC) embedded in a microfluidic channel addressed by fiber-terminated planar waveguides. Experimental demonstrations performed with several ethanol solutions ranging from a purity of 96.00% (n = 1.36356) to 95.04% (n = 1.36377) yielded a sensitivity (Δλ/Δn) of 836 nm/RIU and a limit of detection (LOD) of 6 x 10^-5 RIU, which is, however, still one order of magnitude higher than the theoretical lower limit of the limit of detection 1.3 x 10^–6 RIU. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Denmark)

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Review

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1718 KiB

Open AccessReview

Sensing-Applications of Surface-Based Single Vesicle Arrays

by Sune M. Christensen and Dimitrios G. Stamou

Sensors 2010, 10(12), 11352-11368; https://doi.org/10.3390/s101211352 - 13 Dec 2010

Cited by 44 | Viewed by 14421

Abstract

A single lipid vesicle can be regarded as an autonomous ultra-miniaturised 3D biomimetic “scaffold” (Ø ≥ 13 nm) ideally suited for reconstitution and interrogation of biochemical processes. The enclosing lipid bilayer membrane of a vesicle can be applied for studying binding (protein/lipid or [...] Read more.

A single lipid vesicle can be regarded as an autonomous ultra-miniaturised 3D biomimetic “scaffold” (Ø ≥ 13 nm) ideally suited for reconstitution and interrogation of biochemical processes. The enclosing lipid bilayer membrane of a vesicle can be applied for studying binding (protein/lipid or receptor/ligand interactions) or transmembrane events (membrane permeability or ion channel activation) while the aqueous vesicle lumen can be used for confining few or single macromolecules and probe, e.g., protein folding, catalytic pathways of enzymes or more complex biochemical reactions, such as signal transduction cascades. Immobilisation (arraying) of single vesicles on a solid support is an extremely useful technique that allows detailed characterisation of vesicle preparations using surface sensitive techniques, in particular fluorescence microscopy. Surface-based single vesicle arrays allow a plethora of prototypic sensing applications in a high throughput format with high spatial and high temporal resolution. In this review we present a series of applications of single vesicle arrays for screening/sensing of: membrane curvature dependent protein-lipid interactions, bilayer tension, reactions triggered in the vesicle lumen, the activity of transmembrane protein channels and biological membrane fusion reactions. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Denmark)

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