Electrothermal Device Research Articles

Determination of Cd in food using an electrothermal vaporization capacitively coupled plasma microtorch optical emission microspectrometer: Compliance with European legislation and comparison with graphite furnace atomic absorption spectrometry

A precise, accurate and sensitive method based on electrothermal vaporization capacitively coupled plasma microtorch optical emission spectrometry for Cd determination in various dietary products was developed. The instrumentation is inexpensive as it includes a low power (15 W) and low argon consumption (150 ml min−1) microplasma connected to a small-sized Rh electrothermal vaporization device and a low resolution microspectrometer. The sample was subjected to microwave assisted digestion in HNO3 – H2O2 mixture and Cd was determined in 10 μl sample without preconcentration. The standard addition method was used to compensate for the non-spectral matrix effects. The new method was in-house validated by analyzing certified reference materials and test dietary samples for which the Cd maximum level was established in Commission Regulation 488/2014/EU. The figures of merit of the proposed method and the experimental results were compared to those obtained in graphite furnace atomic absorption spectrometry as standardized method and discussed in relation with the requirements in the Commission Decision 2002/657/EC and Commission Regulations 2011/836/EU and 2007/333/EC. The limit of detection in fresh sample (0.001–0.009 mg kg−1), limit of quantification (0.002–0.018 mg kg−1), recovery (103 ± 15%), trueness (−3.0)–(+7.3)% and precision (0.8–14.0%) were similar to those found in the reference method and comply with the minimal criteria imposed to a method to be used in official laboratories for Cd determination in food. Precision for Cd determination close to maximum admitted levels or higher was of 0.8–6.0%, while for lower concentration in the range 4.0–14.0%. The Bland and Altman statistical test allowed successful evaluation of the new method as an alternative to the well established graphite-furnace atomic absorption spectrometry. The proposed method has analytical potential and is easy to run, while the full miniaturized instrumentation could be considered as a useful tool for the future as an alternative to the traditional instrumentation.

Application of low-cost electrothermal vaporization capacitively coupled plasma microtorch optical emission spectrometry for simultaneous determination of Cd and Pb in environmental samples

The study discusses the applicability and analytical capability of a laboratory miniaturized system including a small-sized electrothermal vaporizer with Rh filament and a low power (15W) and low Ar consumption (150mlmin−1) capacitively coupled plasma microtorch interfaced with a low resolution microspectrometer for the simultaneous determination of Cd and Pb in environmental samples by optical emission spectrometry. Ten-microliter samples were dried (100°C, 80s) and vaporized (1500°C, 6s) by filament heating, then sample vapor was introduced into plasma via an Ar stream and 20 successive emission episodes were recorded with 500ms integration time per episode. The operating parameters of the electrothermal vaporization device and plasma were optimized in order to achieve the simultaneous determination of the two elements with best analytical performance. The method was verified by analyzing CRMs of soil, and then applied to real samples digested in aqua regia. The standard addition method was used to compensate for the non-spectral matrix effects on the analytical signal. Under the optimized conditions the limits of detection were 130±35μgkg−1 (13pg) for Cd at 228.802nm and 2100±175μgkg−1 (210pg) for Pb at 368.346nm. Recovery was in the range 98±18% for Cd and 103±11% for Pb for 95% confidence interval, while the relative standard deviation of repeatability was 4–12% (n=3). The investigated instrumentation has analytical potential and prototyping perspective to be used for toxic element determination in environmental samples.

Theoretical considerations on efficiency degradation due to thermal effect in a planar GaN-based LED with a GaN substrate

In this paper, using a fully-coupled, three-dimensional electro-thermal device simulator, we study the mechanism of efficiency degradation at high current operation in planar GaN-based light emitting diodes (LED). In particular, the improvement of the efficiency degradation using thicker conductive GaN substrates has been demonstrated. First, it is found that local Joule heating inside thin conductive GaN substrates degrades internal quantum efficiency (IQE) and increases the series resistance. Then, we introduced thicker conductive GaN substrates and simulated distributions of the current density and temperature inside the substrate. It is found that the maximum current density inside the GaN substrate decreases by about six times for a 100-µm-thick substrate compared to that for a 5-µm-thick substrate. Therefore, the maximum junction temperature decreases, and then IQE and the driving voltage are improved. The present study proves that thick GaN substrates are effective to improve the properties of planar LEDs at high current operation.

Use of an Electrothermal Bipolar Vessel Sealing Device During Recipient Hepatectomy for Liver Transplantation

Use of an Electrothermal Bipolar Vessel Sealing Device During Recipient Hepatectomy for Liver Transplantation

A Prospective Study of In Vivo and Ex Vivo Sealing of the Human Inferior Mesenteric Artery Using an Electrothermal Bipolar Vessel-Sealing Device

Mesenteric vascular ligation is a critical step in minimally invasive colorectal surgery. This study assessed the quality of in vivo and ex vivo sealing of the human inferior mesenteric artery (IMA), as well as the relation of IMA stump and bursting pressure. This was a prospective experimental study in a tertiary-care teaching hospital. In total, 25 patients were included in the study. For the main outcome measures, bursting pressures were measured for each specimen. Ten freshly sealed specimens were histologically assessed for seal quality and lateral thermal damage. We evaluated 54 specimens from 25 patients for bursting pressure, of which 25 were primary sealed vessels (sealed in vivo at surgery) and 29 were secondary sealed vessels (sealed in the laboratory). The mean bursting pressure was 862 mm Hg. The mean diameter was 4 mm (range, 3-5 mm) with a standard deviation of 1 mm. Pearson correlation showed no correlation between diameter and bursting pressure (P=.187) or the length and bursting pressure (P=.247). There was no statistically significant difference in bursting pressures in the four groups of vessels based on length. One calcified vessel had a significantly lower bursting pressure of 89 mm Hg. There was no intraoperative or postoperative bleeding. Ten sealed specimens were sent for histological evaluation, which showed mean lateral thermal damage of 0.57 mm (range, 0-1.75 mm). The bursting pressure in IMAs sealed with a bipolar device is significantly higher than physiological pressures; thus, the device can be safely used in sealing the vessel during colorectal surgery. Additionally, the length of the vessel stump does not correlate with the bursting pressures. Care needs to be taken when the vessel is calcified, which can be a potential cause of a weak seal.

A miniaturized capacitively coupled plasma microtorch optical emission spectrometer and a Rh coiled-filament as small-sized electrothermal vaporization device for simultaneous determination of volatile elements from liquid microsamples: Spectral and analytical characterization

A low power and low argon consumption (13.56MHz, 15W, 150mlmin−1) capacitively coupled plasma microtorch interfaced with a low-resolution microspectrometer and a small-sized electrothermal vaporization Rh coiled-filament as liquid microsample introduction device into the plasma was investigated for the simultaneous determination of several volatile elements of interest for environment. Constructive details, spectral and analytical characteristics, and optimum operating conditions of the laboratory equipment for the simultaneous determination of Ag, Cd, Cu, Pb and Zn requiring low vaporization power are provided. The method involves drying of 10μl sample at 100°C, vaporization at 1500°C and emission measurement by capture of 20 successive spectral episodes each at an integration time of 500ms. Experiments showed that emission of elements and plasma background were disturbed by the presence of complex matrix and hot Ar flow transporting the microsample into plasma. The emission spectrum of elements is simple, dominated by the resonance lines. The analytical system provided detection limits in the ngml−1 range: 0.5(Ag); 1.5(Cd); 5.6(Cu); 20(Pb) and 3(Zn) and absolute detection limits of the order of pg: 5(Ag); 15(Cd); 56(Cu); 200(Pb) and 30(Zn). It was demonstrated the utility and capability of the miniaturized analytical system in the simultaneous determination of elements in soil and water sediment using the standard addition method to compensate for the non-spectral effects of alkali and earth alkaline elements. The analysis of eight certified reference materials exhibited reliable results with recovery in the range of 95–108% and precision of 0.5–9.0% for the five examined elements. The proposed miniaturized analytical system is attractive due to the simple construction of the electrothermal vaporization device and microtorch, low costs associated to plasma generation, high analytical sensitivity and easy-to-run for simultaneous multielemental analysis of liquid microsamples.

Electro-Thermal Analysis and Optimisation of Edge Termination of Power Diode Supported by 2-D/3-D Numerical Modelling and Simulation

Numerical modelling and simulation provide an efficient tool for analysis and optimization of device structure design. In this paper we present the analysis and the geometry optimization of the power module with high power pin diode structure supported by the advanced 2-D/3-D mixed-mode electro-thermal device simulation. The structure under investigation is P+NN+ power diode device designed for high reverse voltages and very high forward currents, with a maximum forward surge current up to 2.7 kA.

PSPICE circuit simulation of microbolometer infrared detectors with noise sources

In this paper, we present a method of incorporating various types of noise in circuit simulation of a microbolometer infrared detector to analyze the effect of noise on its performance. This ability of simulating electro-thermal performance of microbolometers in circuit simulation platform along with their noise performance allows designing of its suitable readout integrated circuit (ROIC). Being an electro-thermal device, a microbolometer has both the electrical and thermal components interacting with each other. Therefore, the noise sources existing in standard circuit simulators cannot predict the noise of a microbolometer correctly. Disturbances coming from the background radiation, device temperature fluctuations, flicker noise and the Johnson noise etc. contribute in the total noise of a microbolometer element. All these components of noise can be incorporated using the proposed simulation technique. The technique also allows modifying the frequency response of the noise in simulations as per the user defined noise spectrum, making it suitable for any type of microbolometer.

Study of self-heating effects in SOI and conventional MOSFETs with electro-thermal particle-based device simulator

In this paper we present a study of self-heating effects in nanoscale SOI (Silicon-On-Insulator) devices and conventional MOSFETs using an in-house electro-thermal particle-based device simulator. We first describe the key features of the electro-thermal Monte Carlo device simulator (the two-dimensional (2D) and the three-dimensional version (3D) of the tool) and then we present a series of representative simulation results that clearly illustrate the importance of self-heating in larger nanoscale devices made in SOI technology. Our simulation results for planar SOI devices (using 2D version of the tool) show that in the smallest devices considered, heat dissipation occurs in the contacts, not in the active channel region of the device. This is because of two factors: pronounced velocity overshoot effect and the smaller thermal resistance of the buried oxide layer. We propose methods in which heat can be effectively removed from the device by using silicon on diamond and silicon on AlN technologies. To simulate self heating in nanowire transistors, the 2D simulator was extended to three spatial dimensions. We study the interplay of Coulomb interactions due to the presence of a random trap at the source end of the channel in nanowire transistors, the influence of a positive and a negative trap on the magnitude of the on-current and the role of the potential barrier at the source end of the channel. Finally, we examine the importance of self-heating effects in conventional MOSFETs used for low-power applications. We find that the average temperature increase obtained with our simulator of about 10 K is almost identical to the value that has to be used in low-power circuit simulations.

Electro-thermal analysis and optimization of edge termination of power diode supported by 2D numerical modeling and simulation

High reliability and performance of power semiconductor devices depend on an optimized design based on a good understanding of their electro-thermal behavior and of the influence of parasitic components on their operation. This leads to the need for electro-thermal 2/3-D numerical modeling and simulation in power electronics as an efficient tool for analysis and optimization of device structure design and identification of critical regions. In this paper we present an analysis and geometry optimization of a high power pin diode structure supported by advanced 2-D mixed mode electro-thermal device and circuit simulation. Lowering of the operation temperature by better power management and heat dissipation due to an optimized structure design will allow withstanding higher current pulses and suppressing the damage of the analyzed structure by thermal breakdown.

Analysis of reliability and optimization of ESD protection devices supported by modeling and simulation

An analysis of electrostatic discharge (ESD) protection structures supported by advanced 2-D mixed mode electro-thermal device and circuit simulation with calibrated electro-physical models to increase the reliability of protected IC’s is presented. The critical temperature as a criterion of device destruction is defined and experimentally verified. Numerical simulation and visualization of the internal electro-physical properties of the analyzed structures during a very short ESD pulse considerably improved the understanding of their physical behavior and contributes to a proper design and optimization of doping and geometry of the analyzed ESD protection devices. The analyzed devices are designed as protection against Human Body Model (HBM) and International Electromechanical Commission model (IEC) 61000-4-2 with very high robustness. The obtained results are shown on two examples. Modification of the device layout by splitting the cathode contact of the ESD diode into two parts allowing area reduction with improved electrical characteristics is the subject of the first example. The influence of doping fluctuations on the device robustness is presented in the second example. Different triggering and failure mechanisms of the diode and transistor structure during HBM and IEC pulse are presented.

Bipolar Electrothermal Vessel Sealing System and 5-mm 2 Expandable Trocar Approach in Pediatric Laparoscopic Varicocelectomy

To present our initial experience with electrothermal bipolar vessel device and only 2 expandable ports for laparoscopic Palomo varicocele procedure in pediatric and adolescent population. In a 3-year period between 2006 and 2009, sixty-three boys and adolescents diagnosed in our institution as having varicocele underwent Palomo laparoscopic surgery with a two 5-mm expandable-trocar laparoscopic approach using the LigaSure technology (Valleylab Inc., Covidien, Boulder, CO) for spermatic vessels sealing. The outcome variables recorded for analysis were age at presentation, symptoms, varicocele grade based on Dubin and Amelar Classification, testicular atrophy, operative time, complications, recurrence, and reactive hydrocele formation. Mean follow-up was 1.8 years (range, 6 mo to 3 y). Children's age at diagnosis ranged between 9 and 19 years. Mean age at operation was 14.8 ± 1.2 years. All cases were left side varicoceles and 70% had grade III varicocele. Testicular atrophy was noticed in 39.8% of cases. All boys underwent Palomo laparoscopic sealing of the spermatic vessels using bipolar vascular electrothermal device Ligasure with a 2-trocar approach. Mean operative surgery time was 21 minutes. Median hospital stay was 21 ± 8 hours. No conversion cases were registered. Nine patients developed hydrocele after laparoscopic procedure (14.2%). Three patients of these cases underwent Winkelman-Lord's hydrocelectomy (4.7% of total). Laparoscopic Palomo varicocele surgery for pediatric patients using Ligasure as spermatic vessels sealant and only 2 radially expandable 5-mm trocars is a safe, feasible, and time-effective technical improvement.

DESIGN OF A PORTABLE ELECTROTHERMAL VAPORIZATION FLAME ATOMIC EMISSION SPECTROMETRY DEVICE FOR FIELD ANALYSIS

A nontraditional, portable flame atomic emission spectrometry (FAES) device has been constructed using a welding industry metal cutting torch as the flame source with a tungsten coil electrothermal vaporization device for sample introduction. Twenty-microliter sample aliquots were pipetted onto a commercially available tungsten filament, and a home-written Visual Basic program was used to automatically dry and atomize the sample. The sample was then transported into the heart of the air-acetylene flame, where it was excited, and the resulting emission signal was focused onto the entrance of a miniature charge coupled device spectrometer. Figures of merit were determined for five alkaline and alkali earth metals of biological and environmental significance. Limits of detection were, on average, 100 times lower than those for traditional flame emission spectrometers. The capabilities of this portable device make it an ideal tool for biological field analysis, particularly in areas where traditional laboratories are inaccessible.

Design of a compact, aluminum, tungsten-coil electrothermal vaporization device for inductively coupled plasma-optical emission spectrometry

A new compact, aluminum electrothermal vaporization cell was constructed for inductively coupled plasma-optical emission spectrometry analysis. This cell is compact enough to fit within the space occupied by the spray chamber and fits directly to the quartz torch without extraneous tubing through the use of a simple Compression fitting. Sample volumes as low as 10μL were analyzed with an automated control program for efficient vaporization. Twelve elements were analyzed utilizing a time resolved acquisition method so that real-time data could be generated over a period of 10s with an average improvement factor of 14 for elements over a wavelength range of 193–445nm.

Randomized controlled trial of bipolar diathermy vs ultrasonic scalpel for closed hemorrhoidectomy

To compare hemorrhoidectomy with a bipolar electrothermal device or hemorrhoidectomy using an ultrasonically activated scalpel. Sixty patients with grade III or IV hemorrhoids were prospectively randomized to undergo closed hemorrhoidectomy assisted by bipolar diathermy (group 1) or hemorrhoidectomy with the ultrasonic scalpel (group 2). Operative data were recorded, and patients were followed at 1, 3, and 6 wk to evaluate complications. Independent assessors were assigned to obtain postoperative pain scores, oral analgesic requirement and satisfaction scores. Reduced intraoperative blood loss median 0.9 mL (95% CI: 0.8-3.7) vs 4.6 mL (95% CI: 3.8-7.0), P = 0.001 and a short operating time median 16 (95% CI: 14.6-18.2) min vs 31 (95% CI: 28.1-35.3) min, P < 0.0001 was observed in group 1 compared with group 2. There was a trend towards lower postoperative pain scores on day 1 group 1 median 2 (95% CI: 1.8-3.5) vs group 2 median 3 (95% CI: 2.6-4.2), P = 0.135. Reduced oral analgesic requirement during postoperative 24 h after operation median 1 (95% CI: 0.4-0.9) tablet vs 1 (95% CI: 0.9-1.3) tablet, P = 0.006 was observed in group 1 compared with group 2. There was no difference between the two groups in the degree of patient satisfaction or number of postoperative complications. Bipolar diathermy hemorrhoidectomy is quick and bloodless and, although as painful as closed hemorrhoidectomy with the ultrasonic scalpel, is associated with a reduced analgesic requirement immediately after operation.

An evaluation of electrosurgical vessel-sealing devices in biliary tract surgery in a porcine model

ObjectivesThe purpose of this study was to evaluate two electrosurgical vessel-sealing devices in biliary surgery. MethodsPorcine common bile ducts (CBDs) were sealed with two electrosurgical devices, an electrothermal bipolar vessel-sealing device (EBVS) and ultrasonic coagulation shears. Acute study animals underwent surgical bile duct sealing followed by immediate burst pressure testing. Chronic study animals were maintained for 1 week postoperatively and then tested. ResultsThe seal failure rate in the acute study was 50% for both the EBVS device and shears, and 0% for the laparoscopic surgical clip device used as a control. The latter had significantly higher burst pressures (646.2±281.8mmHg; P=0.006) than the EBVS device (97.6±86.6mmHg) and shears (71.7±89.3mmHg). No significant difference in burst pressures was noted between the EBVS device and shears (97.6±86.6mmHg vs. 71.7±89.3mmHg). In the chronic study, obvious bile leaks occurred in one of four pigs (25%) in the EBVS device subgroup and two of four pigs (50%) in the shears subgroup. The average proximal CBD pressure in seven pigs was 16.1±4.1mmHg. The average chronic burst pressure in the control subgroup was 1088.0±922.6mmHg. ConclusionsGiven the high rates of failure of the EBVS device and the shears in consistently sealing biliary ducts, we do not recommend their routine use in biliary surgery.

Electrothermal Monte Carlo Simulation of GaN HEMTs Including Electron–Electron Interactions

A Monte Carlo device simulator was developed to investigate the electronic transport properties in AlGaN/GaN high-electron mobility transistors (HEMTs). Electron-electron interactions were included using a particle-particle-particle-mesh coupling scheme. Quantum corrections were applied to the heterointerface using the effective potential approach due to Ferry. Thermal effects were also included by coupling the particle-based device simulator self-consistently with an energy balance solver for the acoustic and optical phonons. The electrothermal device simulator was used to observe the temperature profiles across the device. Hot spots or regions of higher temperatures were found along the channel in the gate-drain spacing. Results from electrothermal simulations show self-heating degradation of performance at high source-drain bias. More importantly, the observed nonequilibrium phonon effects may play an important role in determining the thermal distribution in these HEMTs, resulting in reliability issues such as current collapse.

Modeling self-heating effects in nanoscale SOI devices

We have developed electro-thermal device simulator that at present self-consistently solves the Boltzmann Transport Equation (BTE) for the electrons and the energy balance equations for acoustic and optical phonons. The simulator has been successfully used in investigation of self-heating effects in different technology nodes of nano-scale fully-depleted (FD) silicon on insulator (SOI) devices and dual gate (DG) device structures. Our simulation results suggest that self-heating has less degrading effect on the on-current in smaller devices in which non-stationary transport and velocity overshoot effect dominate the carrier transport. We also find that the choice of the boundary conditions on the gate (Dirichlet vs. Neumann) has significant impact on the current degradation. The role of Neumann and leaky Dirichlet boundary conditions at the source and drain contact is also examined and estimates on the overall current degradation are presented. Finally we illustrate that the use of anisotropic and temperature dependent thermal conductivity is needed to properly determine the temperature of the hot spot which is important parameter regarding device reliability.

Thermal Effects in Fully-Depleted SOI Devices

In this paper we summarize our research work on electro-thermal modeling of different generations of fully-depleted SOI devices. We first discuss our electro-thermal device simulator that self-consistently couples the Monte Carlo solver for the electrons with the energy balance solver for acoustic and optical phonons. Afterwards we discuss simulation results for different technology fully-depleted SOI devices.

Comparing bipolar electrothermal device and endostapler in endoscopic lung wedge resection

Video-assisted thoracoscopy (VATS) is gaining on thoracic surgery, having newly developed devices next to endostaplers for haemostatic and airtight sealing of lung parenchyma. Though the bipolar electrothermal Ligasure has good results for pulmonary wedge resection, its literature is small in numbers. Authors compared Ligasure and endostapler for pulmonary wedge resection of solitary pulmonary nodules (SPN). Authors performed a retrospective analysis of 44 consecutive patients. The indication of operation was non-verified SPN in all cases. They carried out pulmonary wedge resection for 22 patients with Ligasure-Atlas and 22 patients with ETS Flex endostapler via VATS. Authors examined the gender, average age (62 vs. 49 years), mean hospital stay (6.6 vs. 6.8 days), average operation time (55 vs. 50 min), number of complications (2 vs. 1), average drainage time (2.8 vs. 2.7 days), average fluid loss (190 vs. 160 ml), and instrumental costs (367 euro vs. 756 euro) of both groups. They accomplished the histological analysis of the coagulated lung parenchyma as well. According to the results, the Ligasure-Atlas is eligible for pulmonary wedge resection. The method is safe, easy to use, having minimal rate of complications. It can moderate costs of operation, compared to endostaplers.