Pimenta S.,University of Minho |
Cardoso S.,INESC Microsistemas e Nanotecnologias INESC MN |
Miranda A.,International Iberian Nanotechnology Laboratory |
De Beule P.,International Iberian Nanotechnology Laboratory |
And 2 more authors.
Biomedical Optics Express | Year: 2015
This paper presents the design, optimization and fabrication of 16 MgO/TiO2 and SiO2/TiO2 based high selective narrow bandpass optical filters. Their performance to extract diffuse reflectance and fluorescence signals from gastrointestinal tissue phantoms was successfully evaluated. The obtained results prove their feasibility to correctly extract those spectroscopic signals, through a Spearman’s rank correlation test (Spearman’s correlation coefficient higher than 0.981) performed between the original spectra and the ones obtained using those 16 fabricated optical filters. These results are an important step for the implementation of a miniaturized, low-cost and minimal invasive microsystem that could help in the detection of gastrointestinal dysplasia. © 2015 Optical Society of America.
PubMed | University of Minho, International Iberian Nanotechnology Laboratory and INESC Microsistemas e Nanotecnologias INESC MN
Type: Journal Article | Journal: Biomedical optics express | Year: 2015
This paper presents the design, optimization and fabrication of 16 MgO/TiO2 and SiO2/TiO2 based high selective narrow bandpass optical filters. Their performance to extract diffuse reflectance and fluorescence signals from gastrointestinal tissue phantoms was successfully evaluated. The obtained results prove their feasibility to correctly extract those spectroscopic signals, through a Spearmans rank correlation test (Spearmans correlation coefficient higher than 0.981) performed between the original spectra and the ones obtained using those 16 fabricated optical filters. These results are an important step for the implementation of a miniaturized, low-cost and minimal invasive microsystem that could help in the detection of gastrointestinal dysplasia.
Bi H.,International Iberian Nanotechnology Laboratory |
Duarte C.M.,INESC Microsistemas e Nanotecnologias INESC MN |
Duarte C.M.,University of Lisbon |
Brito M.,International Iberian Nanotechnology Laboratory |
And 5 more authors.
Biosensors and Bioelectronics | Year: 2016
Quantitative analysis of antioxidants in a fast, simple and accurate manner is of great importance in the view of real-time monitoring the health of individuals. Recently, we have developed a UV/vis spectroscopic microfluidic sensor to specifically quantify ascorbic acid based on the immobilization of ascorbate oxidase, a relatively unstable enzyme. In this work, three different strategies for the immobilization of the unstable enzyme, including alumina sol-gel encapsulation, physisorption to PDMS channels with, and without alumina xerogel modification, were compared to build a microsensor. We found that the loading amount of the enzyme is not the determinative factor for the performance of the microfluidic biosensor but the retained activity of the enzyme and diffusion in the microfluidic channel. Taking into account of the two factors, the protocol of adsorbing enzymes to alumina (Al2O3) xerogel modified PDMS surface was demonstrated to be the best for preparing the microfluidic sensor among the utilized protocols. The microsensor prepared under the optimized protocol was further used to quantify ascorbic acid in human blood, where only dozens of microliters of blood (few drops) was required, demonstrating its potential application in clinical diagnosis. The developed strategy is featured with optimized enzymatic activity, simple process of microfluidic platform, low sample consumption, and straightforward spectrophotometry based detection. © 2016 Elsevier B.V.
Donolato M.,Polytechnic of Milan |
Sogne E.,Polytechnic of Milan |
Dalslet B.T.,Technical University of Denmark |
Cantoni M.,Polytechnic of Milan |
And 7 more authors.
Applied Physics Letters | Year: 2011
We demonstrate the detection of the Brownian relaxation frequency of 250 nm diameter magnetic beads using a lab-on-chip platform based on current lines for exciting the beads with alternating magnetic fields and highly sensitive magnetic tunnel junction (MTJ) sensors with a superparamagnetic free layer. The first harmonic out-of-phase component of the MTJ response gives the imaginary part of the magnetic bead susceptibility, which peaks at the Brownian relaxation frequency. This work paves the way to on-chip implementation of Brownian magnetorelaxometry in innovative "lab-on-a-bead" assays for biomolecular recognition. © 2011 American Institute of Physics.
Martins S.A.M.,INESC Microsistemas e Nanotecnologias INESC MN |
Martins S.A.M.,IN Institute of Nanoscience and Nanotechnology |
Martins S.A.M.,IBB Institute for Biotechnology And Bioengineering |
Moulas G.,INESC Microsistemas e Nanotecnologias INESC MN |
And 11 more authors.
Biosensors and Bioelectronics | Year: 2014
G-protein coupled receptor (GPCRs) drug discovery is a thriving strategy in the pharmaceutical industry. The standard approach uses living cells to test millions of compounds in a high-throughput format. Typically, changes in the intracellular levels of key elements in the signaling cascade are monitored using fluorescence or luminescence read-out systems, which require external equipment for signal acquisition. In this work, thin-film amorphous silicon photodiodes with an integrated fluorescence filter were developed to capture the intracellular calcium dynamics in response to the activation of the endogenous muscarinic M1 GPCR of HEK 293T cells. Using the new device it was possible to characterize the potency of carbachol (EC50=10.5μM) and pirenzepine (IC50=4.2μM), with the same accuracy as standard microscopy optical systems. The smaller foot-print provided by the detection system makes it an ideal candidate for the future integration in microfluidic devices for drug discovery. © 2013 Elsevier B.V.
Cardoso F.A.,INESC Microsistemas e Nanotecnologias INESC MN |
Costa T.,INESC Investigacao e Desenvolvimento INESC ID |
Costa T.,University of Lisbon |
Germano J.,INESC Investigacao e Desenvolvimento INESC ID |
And 10 more authors.
IEEE Transactions on Magnetics | Year: 2012
Since 2006, fully scalable matrix-based magnetoresistive biochips have been proposed. This integration was initially achieved with thin film switching devices and moved to complementary metal-oxide-semiconductor (CMOS) switching devices and electronics. In this paper, a new microfabrication process is proposed to integrate magnetoresistive sensors on a small CMOS chip (4 mm 2). This chip includes a current generator, multiplexers, and a diode in series with a spin valve as matrix element. In this configuration, it is shown that the fabricated spin-valves have similar magnetic characteristics when compared to standalone spin valves. This validates the successfulness of the developed microfabrication process. The noise of each matrix element is further characterized and compared to the noise of a standalone spin valve and a portable electronic platform designed to perform biological assays. Although the noise is still higher, the spin valve integrated on the CMOS chip enables an increase in density and compactness of the measuring electronics. © 1965-2012 IEEE.
Serrate D.,University of Zaragoza |
De Teresa J.M.,University of Zaragoza |
Marquina C.,University of Zaragoza |
Marzo J.,University of Zaragoza |
And 5 more authors.
Biosensors and Bioelectronics | Year: 2012
The combination of magnetoresistive sensors and magnetic labeling of bioanalytes, which are selectively captured by their complementary antibody in the proximity of the sensor is a powerful method in order to attain truly quantitative immunological assays. In this paper we present a technical solution to exploit the existing spin valve technology to readout magnetic signals of bio-functionalized magnetic nanoparticles. The method is simple and reliable, and it is based on a discrete scan of lateral flow strips with a precise control of the contact force between sensor and sample. It is shown that the signal of the sensor is proportional to the local magnetization produced by the nanoparticles in a wide range of concentrations, and the sensitivity thresholds in both calibration samples and real immunorecognition assays of human chorionic gonadotropin hormone are well below the visual inspection limit (5.5. ng/ml). Furthermore the sample scanning approach and the reduced dimensions of the sensors provide unprecedented spatial resolution of the nanoparticle distribution across the supporting nitrocellulose strip, therefore enabling on-stick control references and multi-analyte capability. © 2012 Elsevier B.V.
Zhang Z.H.,University of Manitoba |
Gui Y.S.,University of Manitoba |
Fu L.,University of Manitoba |
Fan X.L.,Lanzhou University |
And 7 more authors.
Physical Review Letters | Year: 2012
An intrinsic thermoelectric coupling effect in the linear response regime of magnetic tunneling junctions (MTJ) is reported. In the dc response, it leads to a nonlinear correction to Ohm's law. Dynamically, it enables a novel Seebeck rectification and second harmonic generation, which apply for a broad frequency range and can be magnetically controlled. A phenomenological model on the footing of the Onsager reciprocal relation and the principle of energy conservation explains very well the experimental results obtained from both dc and frequency-dependent transport measurements performed up to GHz frequencies. Our work refines previous understanding of magnetotransport and microwave rectification in MTJs. It forms a new foundation for utilizing spin caloritronics in high-frequency applications. © 2012 American Physical Society.