José Amaral

Design for recycling in the automobile industry: new approaches and new tools

This paper presents novel design for recycling (DfR) strategies that were incorporated in a new software tool, combining the use of emerging technologies dedicated to automobile shredder residue recycling, together with design for dismantling strategies. Extended producer responsibility enforces manufacturers to maintain product responsibility along its life cycle. As a consequence, manufacturers are under pressure to dispose of products in an environmentally responsible manner. The auto industry has been particularly involved in these processes and, in particular, European Union directives stipulate minimum reuse and recovery rates for end-of-life vehicles. This framework provides a motivation for the increasing use of dedicated design for recycling tools and practices. The current end-of-life vehicle processing is embodied by two industries: dismantling and shredding. If until recently dismantling was a key strategy in DfR, the auto industry has been investing in the development of automated technologies to promote the recycling of automobile shredder residue, as an alternative of more labour-intensive dismantling activities. However, existing DfR tools emphasize design for dismantling as a major DfR strategy, based on the belief that a product is to be disassembled at the end of its life. This paper introduces a new approach that includes, as an end-of-life processing strategy, postshredding sorting of materials and subsequent recycling, and describes a new DfR tool that provides the identification of economically optimum recycling strategies aimed at achieving given recycling and reuse rates, by adequately combining dismantling, shredding, and postshredding activities.

Disposable immunosensors for C-reactive protein based on carbon nanotubes field effect transistors.

Label-free immunosensors based on single-walled carbon nanotubes field effect transistor (NTFET) devices were developed for the detection of C-reactive protein (CRP) which is currently the best validated inflammatory biomarker associated with cardiovascular diseases. The immunoreaction principle consists in the direct adsorption of CRP specific antibodies (anti-CRP) to single-walled carbon nanotubes (SWCNTs) networks. Such anti-CRP are the molecular receptors of CRP antigens which, in turn, can be detected by the developed NTFET devices in a linear dynamic range of 10(-4)-10(2) μg/mL. Thus, typical values of CRP (in blood serum) for healthy persons (<1 μg/mL), and higher levels (>5 μg/mL) corresponding to pathological states, can be both detected with the NTFET immunosensors, becoming an advantageous alternative as the basis for the development of analytical instrumentation for assessment of risk of occurrence of cardiovascular diseases. A log-log linear regression was applied to the experimental data with a correlation coefficient of r=0.9962 (p<0.001), and there is no statistical difference (from ANOVA) between individual NTFET devices (p=0.9582), demonstrating acceptable reproducibility. According to the experimental results, the estimate of detection limit (LOD, 10(-4)μg/mL) is 3-fold lower than that of some conventional immunoassay techniques for blood serum (e.g., LOD of 0.2 μg/mL for high-sensitivity enzyme-linked immunosorbent assay), and the dynamic range (10(-4)-10(2)μg/mL) is about 6-fold higher. Furthermore, this simple and low-cost methodology allows the use of sample volumes as low as 1 μL for the label-free detection of CRP.

Toward a system to measure action potential on mice brain slices with local magnetoresistive probes

This work combines an electrophysiological system with a magnetoresistive chip to measure the magnetic field created by the synaptic/action potential currents. The chip, with 15 spin valve sensors, was designed to be integrated in a recording chamber for submerged mice brain slices used for synaptic potential measurements. Under stimulation (rectangular pulses of 0.1 ms every 10 s) through a concentric electrode placed near the CA3/CA1 border of the hippocampus, the spin valve sensor readout signals with 20 μV amplitude and a pulse length of 20 to 30 ms were recorded only in the pyramidal cell bodies region and can be interpreted as being derived from action potentials/currents.

OPTIMIZATION AND INTEGRATION OF MAGNETORESISTIVE SENSORS

This paper addresses challenging issues related to the integration of magnetoresistive (MR) sensors in applications such as magnetic field mapping, magnetic bead detection in microfluidic channels, or biochips. Although sharing the same technological principle for detection (magnetoresistance effect), each application has unique specifications in terms of noise, sensitivity, spatial resolution, electrical robustness or geometric constraints. These differences are of high impact for manufacturing, because some strategies used for sensor optimization compromise the freedom for device architecture.

Integration of TMR Sensors in Silicon Microneedles for Magnetic Measurements of Neurons

In this work an alternative neuroscience tool for electromagnetic measurements of neurons at the level of individual cells is developed. To perform such measurements we propose the integration of an array of magnetoresistive sensors on micro-machined Si probes capable of being inserted within the brain without further damage. Si-etch based micromachining process for neural probes is demonstrated in the manufacture of a probe with 15 magnetoresistive sensors in the tip of each shaft. Magnetic tunnel junction sensors with dimensions of 30 μm × 2 μm, sensitivities of 3.32 V/T and detectivity of ≈13 nT/Sqrt (Hz) are placed in the end of the sharply defined probe tips. In order to measure the small signals coming from the neurons, a homemade signal amplifying system was used with a noise level of 240 n VRMS for the system bandwidth. The full system noise is 2772 n VRMS.

Strategies for pTesla Field Detection Using Magnetoresistive Sensors With a Soft Pinned Sensing Layer

The detection of low-intensity and low-frequency signals requires magnetic sensors with enhanced sensitivity, low noise levels, and improved field detection at low operating frequencies. Two strategies to improve the detectivity levels of devices based on tunnel magnetoresistive sensors are demonstrated: 1) a large number of sensors connected in series or 2) an individual sensor with a large sensing area and integrated magnetic flux guides. State-of-the-art MgO-based magnetic tunnel junctions with a soft pinned sensing layer were used in this paper. For 952 sensors in series a sensitivity of 29.3%/mT and a detection level of 455 pT/Hz1/2 were obtained at 100 Hz, whereas the integration of magnetic flux guides in a single sensor yielded a sensitivity of 138.3%/mT and a detection level of 576 pT/Hz1/2 at the same frequency. These two strategies imply a large device footprint, being suitable when a high spatial resolution is not an application requirement.

A Neuronal Signal Detector for Biologically Generated Magnetic Fields

This paper presents a neuronal signal detector for biologically generated magnetic fields. The system includes a hardware section implemented with discrete electronics, which has an ultralow-noise dc or dc+ac current source for magnetoresistive sensor biasing, and signal amplification and filtering, and a software interface that allows signal demodulation, visualization, and digital postprocessing. Compared with the previous measurement setup, the results show that, for the same bandwidth, the proposed instrumentation system has approximately 50 times better noise performance, making the sensor noise the dominant noise source. The system is able to record the magnetic field generated by ionic currents from action potentials of in vitro experiments with mice brain slices. In addition, to obtain an increased spatial resolution, by scaling the number of sensors that can be read, and to enhance the system immunity to external interferences, two integrated circuits with an ultralow-noise current source for MR biasing and a low-noise variable gain amplifier were developed and are also presented.

Electrical ammeter based on spin-valve sensor

The present work shows an electrical ammeter for laboratory purpose based on a magnetoresistive (MR) spin-valve (SV) sensor. The proposed ammeter measures a 10 A maximum current and offers a maximum frequency response between 150 and 800 kHz depending on the electronics whole gain. These features are due to the use of a new generation MR-SV current sensor and a conditioning electronics that compensates in frequency and temperature the sensor response. With little adjustments in the electronics and changing the position of the sensor with respect to current carrying conductor, the designed instrument is able to measure higher current levels. The work shows the proposed ammeter with its different subsystems and describes the procedure used to test the instrument. Also a discussion of the obtained experimental results is included.

An instrumentation system based on magnetoresistive sensors for neuronal signal detection

This paper presents an instrumentation system based on magnetoresistive sensors for neuronal signal detection. The system includes a hardware section, which provides ultra-low noise magnetoresistive sensor biasing, signal amplification and filtering, and a software interface that allows signal visualizations and digital post processing. The results show that, compared to the current measurement setup, the proposed instrumentation system increases the measurement bandwidth from 70 Hz to 2.75 kHz, and reduces the integrated noise in the signal bandwidth from 1 μVRMS to 814 nVRMS.