
L.M. GoncalvesUniversity of Minho · Center for MicroElectromechanical Systems
L.M. Goncalves
Phd
About
186
Publications
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2,991
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Introduction
Working on Next generation monitoring of coastal ecosystems
Working on Thermoelectric thin-films for energy harvesting applications
http://www.mems.dei.uminho.pt/
Additional affiliations
January 2004 - June 2015
January 2004 - December 2007
Education
September 2003 - July 2008
September 1997 - July 1999
Publications
Publications (186)
This paper presents glassy films of lithium phosphorus oxynitride electrolyte with an amorphous structure and improved ionic conductivity suitable for solid‐state batteries. The films of lithium phosphorus oxynitride electrolyte were obtained by deposition using the RF sputtering technique in a reactive N2 atmosphere. The measurements showed films...
Microsystems technologies were applied in the fabrication of thermoelectric (TE) microconverters. Common techniques used in
microelectromechanical systems (MEMS) fabrication, namely wet etching, lift-off (with SU-8 photoresist), reactive ion etching
(RIE), and lithography-electroplating-molding, were compared in the fabrication process of TE micros...
The optimization of the thermal co-evaporation deposition process for n-type bismuth telluride (Bi2Te3) thin films deposited onto polyimide substrates and intended for thermoelectric applications is reported. The influence of deposition parameters (evaporation rate and substrate temperature) on film composition and thermoelectric properties was stu...
The proliferation of certain phytoplankton species may lead to harmful algal blooms (HABs) that can affect living resources and human health. Therefore, an accurate identification of phytoplankton populations is essential for the sustainable management of some activities relevant for the blue economy, such as aquaculture, being also relevant for en...
The ocean has a huge impact on our way of life; therefore, there is a need to monitor and protect its biodiversity [...]
Biofouling is the major factor that limits long-term monitoring studies with automated optical instruments. Protection of the sensing areas, surfaces, and structural housing of the sensors must be considered to deliver reliable data without the need for cleaning or maintenance. In this work, we present the design and field validation of different t...
This chapter presents an overview of energy harvesting systems for powering stand-alone microsystems. The overview is not intended to be exhaustive, but comprehensive enough to catch the importance of energy harvesting in the context of distributed sensor networks. Applications for three types of energy harvesting sources are presented: thermoelect...
Robust wireless communication networks are a cornerstone of the modern world, allowing data to be transferred quickly and reliably. Establishing such a network at sea, a Maritime Internet of Things (MIoT), would enhance services related to safety and security at sea, environmental protection, and research. However, given the remote and harsh nature...
This paper presents the absorbance and fluorescence optical properties of various phytoplankton species, looking to achieve an accurate method to detect and identify a number of phytoplankton taxonomic groups. The methodology to select the excitation and detection wavelengths that results in superior identification of phytoplankton is reported. The...
A linear electromagnetic energy harvesting device for underwater applications, fabricated with a simple manufacturing process, was developed to operate with movement frequencies from 0.1 to 0.4 Hz. The generator has two coils, and the effect of the combination of the two coils was investigated. The experimental study has shown that the energy captu...
The agri-food industry has historically determined the socioeconomic characteristics of Galicia and Northern Portugal, and it was recently identified as an area for collaboration in the Euroregion. In particular, there is a need for action to help to ensure the provision of safe and healthy foods by taking advantage of key enabling technologies. Th...
This chapter presents an overview of energy harvesting systems for powering stand-alone microsystems (MSTs). The overview is not intended to be exaustive, but compreensive enough to catch the importance of energy harvesting in the context of distributed sensors networks. Applications for three types of energy harvesting sources are presented: therm...
The sedimentary processes play a major role in every aquatic ecosystem, however, there are few automated options for in-situ monitoring of sediment displacement in the streambed of waterways. We present an automated optical instrument for in-situ continuous monitoring of sediment deposition and erosion of the streambed that requires no calibration....
Power conversion efficiency (PCE) has been one of the key concerns for power management circuits (PMC) due to the low output power of the vibrational energy harvesters. This work reports a dynamic threshold cancellation technique for a high-power conversion efficiency CMOS rectifier. The proposed rectifier consists of two stages, one passive stage...
During the last decade, the development of different technologies for determining oxygen has undergone a great expansion in favour of industrial developments and the dilemmas it presents to engineering. Dissolved oxygen monitoring by colorimetry, and electrochemical sensors presents several difficulties for long-term application and without constan...
Estuaries have the particularity of being in constant change concerning the salinity of the water, since the river carries fresh water to the mouth, while the force of the tide pushes salty water upstream, reaching several kilometers upstream given the right conditions. These bodies of water do not mix instantly, allowing the appearance of a distin...
The advanced and widespread use of microfluidic devices, which are usually fabricated in polydimethylsiloxane (PDMS), requires the integration of many sensors, always compatible with microfluidic fabrication processes. Moreover, current limitations of the existing optical and electrochemical oxygen sensors regarding long-term stability due to senso...
Coupling together the pyroelectric effect and the photovoltaic effect is a novel method to significantly enhance the performance of photodetectors. In this work, we make use of this effect through a tri-layered heterojunction of n-Si/p-SnOx/n-ZnO, which takes advantage of the pyroelectric properties of the n-type ZnO film and the photovoltaic respo...
Spin-coated chalcostibite CuSbS2 thin films (≈500 nm thick) were fabricated and the influence of the drying temperature on the structural, morphological, optical and thermoelectric properties of the films was investigated. Crystalline phase-pure chalcostibite has been obtained for the films dried at 180 oC and 210 °C, while below 180 o C these film...
Thermoelectric (TE) generators allow the direct conversion of heat into electricity without moving parts and with little maintenance needs if carefully designed. However, their high cost per unit power produced has prevented their widespread use in waste heat recovery applications. The use of earth-abundant, affordable, non-toxic and performant TE...
Endow the implant with intrinsic communication system between sensors and actuators or between implant and patient is a key factor for its long-term success. The capacity of early diagnosis of failures and the ability to remedy them are necessary to minimize expensive complications and reducing revision procedures. Ti6Al4V is the most used titanium...
This article describes the fabrication of MgF2 and MgO thin-film-based optical filters and compares the optical transmission of the filters over UV. The MgF2 thin-films were deposited by use of an e-beam technique and their optical properties were characterised by ellipsometry. The effect of substrate temperature on the optical properties was studi...
The concept of high electrocatalytic activity for chlorine generation has been pioneered through the development of a new system to prevent biofouling onto marine optical sensors surfaces. A combination of impregnated platinum (Pt) nanoparticles into the surface of fluorine tin oxide (FTO) was developed to create high optical transparent electrodes...
This article proposes a nanoscale complementary metal-oxide-semiconductor (CMOS) current reference design for low power analog and digital devices. A self-biased circuit is developed within the current reference. The current reference can compensate for temperature changes and voltage fluctuations. Simulation results showed a low current around 12...
A cost-effective optical instrument for continuous in-situ monitoring applications is presented. With a production cost in raw materials of 38 €, a power consumption of 300 A in sleep mode and 100 mA in active mode (5 ms reading), and a capacity to monitor turbidity and sedimentary displacement at eight different depths in the water column, the sen...
Energy harvesting devices can increase autonomy of submersible marine sensors. However, only the water movements can be used as energy source, since neither solar or temperature gradients are available bellow surface waters. A Linear Electromagnetic Generator (LEG), in a milliwatt energy harvester, is presented. Any moving parts are in contact with...
Salinity measurement in water is typically performed with conductivity sensors. However, for long-term marine deployments, loss of precision is observed, mainly due to electrode drift (oxidation and degradation occurs in the presence of water, salts and bio-fouling), which results in inaccuracy of measurements. A cost-effective, low-power, four-pro...
The photovoltaic (PV) response of SnOx/Si heterojunctions (HJs) through the change of the SnO and SnO2 ratio in the samples that allows us to obtain p or n-type SnOx films is investigated in this work. The values of short-circuit photocurrent density (Jsc), open-circuit voltage (VOC), fill factor (FF) and power conversion efficiency (PCE) are found...
This paper presents a cost- and time-effective wearable inertial sensor system, the InertialLAB. It includes gyroscopes and accelerometers for the real-time monitoring of 3D-angular velocity and 3D-acceleration of up to six lower limbs and trunk segment and sagittal joint angle up to six joints. InertialLAB followed an open architecture with a low...
The invention consists of a new system and method thereof that implements the recovery of heat from a variable thermal load application and the delivery and spreading of this heat at a controllable temperature range to the target application such as a thermoelectric generator. The invention comprises a heat spreader (3) located between the hot sour...
The invention consists of a new system and method thereof that implements the recovery of heat from a variable thermal load application and the delivery and spreading of this heat at a controllable temperature range to the target application such as a thermoelectric generator. The invention comprises a heat spreader (3) located between the hot sour...
Currently, the automotive industry faces challenges to implement solutions that provide reductions in energy consumption, pollutants and greenhouse-gas (GHG) emissions. Exhaust heat recovery employing Thermoelectric generators (TEGs) enables the direct conversion of heat into electric energy without moving parts and little to no maintenance. On-boa...
The authors wish to make the following erratum to this paper [...]
One of the main obstacles for the use of thermoelectric generators (TEGs) in vehicles is the highly variable thermal loads typical of driving cycles. Under these conditions it will be virtually impossible for a conventional heat exchanger to avoid both thermal dilution under low thermal loads and TEG overheating under high thermal loads. The author...
A cost-effective optical sensor for continuous in-situ monitoring of turbidity and suspended particulate matter concentration (SPM), with a production cost in raw materials less than 20 €, is presented for marine or fluvial applications. The sensor uses an infrared LED and three photodetectors with three different positions related to the light sou...
A flexible and ultralight planar thermoelectric generator based on 15 thermocouples composed by n-type bismuth telluride (Bi2Te3) and p-type antimony telluride (Sb2Te3) legs (each with 400 nm thick) connected in series, on 25 - µm thick Kapton® substrate, was fabricated with impressive power factor values of 2.7 mW K-2 m-1 and 0.8 mW K-2 m-1 (at 29...
The advances in wireless communications are still very limited when intended to be used on Underwater Communication Systems mainly due to the adverse proprieties of the submarine channel to the acoustic and radio frequency (RF) waves propagation. This work describes the development and characterization of a polyvinylidene difluoride ultrasound tran...
Here, the ability of using p-type tin oxide (SnOx) thin films as a thermal sensor has been investigated. Firstly, the thermoelectric performance was optimized by controlling the thickness of the SnOx film from 60 up to 160 nm. A high Seebeck coefficient of + 263 µVK-1 and electrical conductivity of 4.1 × 102 (S m-1) were achieved in a 60 nm-thick S...
This paper presents a novel lab-on-a-chip for seawater pH measurement that features in-situ, autonomous, long-term and low-cost measurements. It comprises a poly(dimethylsiloxane) microfluidic system and an integrated low-cost optical-electronic system that uses light emitting diodes as light source and photodiodes as the detectors. The pH measurem...
The development of smart biomedical implants with intrinsic communication system between sensors and actuators, or between implant and patient, remains a challenge for scientific community. Titanium and its alloys, especially Ti6Al4V, are the most used materials in the implant's fabrication. The present work is concerned with implant internal commu...
A cost-effective (less than 20€) and low-power device is present for in situ continuous monitoring of suspended sediments (SPM) concentration in estuarine and coastal areas. The sensor uses nephelometric technique for SPM values less than 20g/L and backscatter technique for higher ones. A transmitted infrared (IR) and ultraviolet (UV) channels are...
In this work, commercial vapor grown carbon nanofibers (CNF), produced by chemical vapor deposition (CVD), were melt extruded with polypropylene (PP) with the aim of analyzing their thermoelectric properties (i.e., electrical conductivity, thermoelectric power, power factor and figure of merit). Unexpectedly, all PP/CNF composites showed negative t...
Electrical conductivity and Seebeck coefficient of freestanding paper of graphene oxide (GO) and GO reduced by heat treatment at 180 °C (rGO) are tuned by addition of carbon nanotubes (CNT). The electrical conductivity of rGO with 50% of CNT is raised to ~2940 S/m from ~613 S/m for pure rGO or ~34 S/m for GO with 50% of CNT without reduction. Moreo...
The number of falls is growing as the main
cause of injuries and deaths in the geriatric community. As
a result, also the cost of treating the injuries associated with
falls is increasing. Thus, the development of fall detection and
prediction systems with the capability of real-time monitoring
without user restriction is imperative. For this reaso...
The influence of substrate type in boosting thermoelectric properties of co-evaporated Bi2Te3 and Sb2Te3 films (with 400 nm-thick) is here reported. Optimized power factor values are 2.7 × 10−3 W K−2 m−1 and 1.4 × 10−3 W K−2 m−1 for flexible Bi2Te3 and Sb2Te3 films, respectively. This is an important result as it is at least 2 times higher than the...
Improved thermoelectric properties of p-Sb2Te3 and n-Bi2Te3 films deposited by thermal co-evaporation at 503 K and 543 K, respectively, are reported, by using two types of substrate (borosilicate glass and 25 μm - Kapton® polyimide). Seebeck coefficients of 194 μV K⁻¹ and - 233 μV K⁻¹ and electrical conductivities of 3.2 × 10⁴ (Ω m)⁻¹ and 5.0 × 10⁴...
Presently 3D printers are gaining widespread attention by both biomedical research and industrial community. 3D printing is a process based on 3D additive manufacturing technology, in which a three-dimensional object is created by gradually adding successive layers of a material under computer control. This paper shows the ability of the desktop 3D...
One of the ways to improve the efficiency of vehicles is to recover a portion of the engine exhaust enthalpy using thermoelectric generators (TEGs). One of the main obstacles for the use of these devices in vehicles is their limitations for operation under the highly variable thermal loads typical of driving cycles. Under these conditions it will b...
This work presents a marine energy harvesting
device to increase energy autonomy of moored oceanographic
monitoring stations. Oscillations and currents through the sea or
river are used to produce energy when the whole system is
submerged to a depth between 3 to 10 meters. In order to have an
inexpensive system, a buoy containing a Linear Electroma...