Design Process Of Devices Research Articles

RapidNAM: generative manufacturing approach of nasoalveolar molding devices for presurgical cleft lip and palate treatment.

Nasoalveolar molding (NAM) is an accepted treatment strategy in presurgical cleft therapy. The major drawbacks of the treatment listed in the literature relate to the time of the treatment and the coordination of the required interdisciplinary team of therapists, parents, and patients. To overcome these limitations, we present the automated RapidNAM concept that facilitates the design and manufacturing process of NAM devices, and that allows the virtual modification and subsequent manufacture of the devices in advance, with a growth prediction factor adapted to the patient's natural growth. The RapidNAM concept involves (i) the prediction of three trajectories that envelope the fragmented alveolar segments with the goal to mimic a harmonic arch, (ii) the extrusion from the larger toward the smaller alveolar segment along the envelope curves toward the harmonic upper alveolar arch, and (iii) the generation of the NAM device with a ventilation hole, fixation pin, and fixation points for the nasal stents. A feasibility study for a vector-based approach was successfully conducted for unilateral and bilateral cleft lip and palate (CLP) patients. A comparison of the modified target models with the reference target models showed similar results. For further improvement, the number of landmarks used to modify the models was increased by a curve-based approach.

Systematic study of Ge1−xSnx absorption coefficient and refractive index for the device applications of Si-based optoelectronics

The absorption coefficient and refractive index of Ge1−xSnx alloys (x from 0% to 10%) were characterized for the wavelength range from 1500 to 2500 nm via spectroscopic ellipsometry at room temperature. By applying physical models to fit the obtained data, two empirical formulae with extracted constants and coefficients were developed: (1) Absorption coefficient. The absorption regarding Urbach tail, indirect and direct bandgap transitions were comprehensively taken into account; (2) refractive index. The Sellmeier coefficients associated with dispersion relationship were extracted. In these formulae, the Sn composition and strain percentage were the input parameters, by inputting which the spectral absorption coefficient and spectral refractive index can be obtained. Since the absorption coefficient is key information to determine the performance of the photodetectors including operation wavelength range, responsivity, and specific detectivity, and the refractive index is very useful for the design of the anti-reflection coating for photodetectors and the layer structure for waveguides, the developed formulae could simplify the optoelectronic device design process due to their parameter-based expressions.

Study of high-tech process furnace using inherently safer design strategies (IV). Advanced NAND device design and thin film process adjustment

According to perspective of process design, using inherently safer design (ISD) strategies could obtain relatively safe levels, while meeting the existing product specification requirements. The experiences for semiconductor manufacturing processes in Taiwan were planning and completed civil construction first, and then followed regulatory limits to provide the maximum piping and equipment for process production line installed in facility area, unlike the general petrochemical industry planning program considerations, indeed often ignored safety consideration. The proposed configuration was the first time applied in NAND (abbreviation of Not AND) flash component technology. There have been no similar schemes used before as in this study, and also the industry has little exploration in this way. It is an important outcome of this study. In this study case, silane (SiH4) was changed to Tetraethyl Orthosilicate (TEOS) for the process to fit ISD substitution strategy of the overall wafer products, under product specification requirements, the more hazardous gaseous silane was replaced by liquid TEOS, thus, even if both have potential hazards of fire, explosion, and poisoning, as the liquid is less likely than gas to leak or diffuse, the potential hazards are reduced, rendering it inherently safer. In this study the potential hazards scenario of 22 nm NAND Flash were analyzed first, then established process design proposal of 22 nm NAND Flash; the design proposal was created according to the above potential hazard analysis results, then process design proposal simulation and verification were presented, followed by process design proposal experiment and verification in 12″ tube, 16 batches of 22 nm NAND Flash. There are 25 wafers per batch, and 16 batches of wafer cassettes tested according to the simulation results. The experiment result showed that the product yield increased from 83.88% of SiH4 to 84.25% of TEOS, which was good because the wafer surface defect is well controlled and the various processes have no significant deviation; the direct current (DC) property improvement was increased from 6.16% to 6.76%, which might be due to the more dense liquid reaction with TEOS. In addition, the frequency response improvement increased from 4.97% to 5.16%, due to the dense material related. Finally, the peeling ability improvement also increased from 4.27% to 4.36%, as the TEOS liquid reaction was. The proposed process design improvement, as created in this study, could meet the expected process goals.

Evaluation of Indicators Supporting the Sustainable Design of Electronic Systems

Engineers are confronted with difficulties when it comes to the inclusion of sustainability aspects into the design process of electronic devices. Due to the specific nature and complexity of material composition, process flows and data availability there is a need for electronics-specific methodologies for environmental assessment. These need to allow for easy adaptation in all stages of the design process thus leading to a rapid identification of critical hotspots in system design. To fulfil this demand, indicators available for product-level assessment are evaluated with regard to environmental impact category coverage, practicability and significance for selected application fields of electronics. Case studies on sensor nodes and lighting products are used to show the application of indicator sets in industrial settings. As an outcome, indicator sets are identified that support the designer in keeping track of the overall sustainability of electronic products.

Computer-aided tolerance allocation of compliant ortho-planar spring mechanism

The allocation of the right tolerances is one of the most important phases in the design process of mechanical devices and systems. In general, the choice has to take into account the manufacturing costs and limitations, looking at the specific functionality of the device and the assemblability of parts. In the case of flexible components, the designer has to include the evaluation of the compliance effects and the structural resistance. The paper discusses a numerical methodology for addressing the problem of the geometrical tolerance allocation for the compliant ortho-planar spring. The methodology is based on the definition of the functionality and resistance objective functions by means of finite element models. Numerical constrained optimisation is then applied to find the suitable combination of tolerance parameters acting on the main dimensions.

Study on evaporation from alloys used in microwave vacuum electron devices

The development of modern satellite communication technologies is imposing higher demands on the lifetime and reliability of the microwave vacuum electronic devices, which directly depend on the evaporation properties of the extensively used Monel and stainless steel. Therefore, it is of vital importance to study the evaporation properties of these two types of metallic materials. For the first time, as far as we know, this paper proposes to study the evaporation properties of metallic materials using time-of-flight mass spectrometer (TOFMS). The components and the contents of the vacuum background, the evaporants from the Monel and from the stainless steel have been measured using the TOFMS, respectively. After the pressure of the measurement chamber is below 4.010-8 Pa, the TOFMS is used for the metallic materials working at different temperatures. They are respectively acquired when the Monel and stainless steel are at room temperature on operate between 750 to 900 ℃ under a pressure of 1.010-6 Pa. The measurements are carried out rapidly and in high sensitivity. As disclosed by the measurements, Mn and Cu began to evaporate when the Monel and the stainless steel are heated to 800 ℃, which is still far below the melting points of the two alloys (1243 ℃ and 1080 ℃). When the Monel and the stainless steel are further heated to 900 ℃, the evaporation of Mn, Cu, and Cr becomes quite considerable. Once the evaporated Mn, Cu, or Cr deposit on the ceramics for the insulation in an electron gun, its insulation will be deteriorated. Hence, the Monel and the stainless steel are not suitable to be use as the components in cathode electron guns, especially those used in the devices that are to work a long lifetime in high vacuum. Moreover, the Monel and the stainless steel are not suitable for used as the components that are often under the electron bombardment, e.g., anodes and collectors, either. The SEM images and XRD of the heat treated surface structures of the Monel and the stainless steel in ultrahigh vacuum (1.010-6 Pa) have also been studied. On heating at 900 ℃ for 30 and 120 min the surface structure and composition change remarkably and a significant reduction in Mn and Cr is visible, and also a large number of holes and crystal boundaries emerge on the surfaces of the two metallic alloys. With increasing heating time, the boundaries will grow larger and larger. As a result, the strength of the two metallic materials becomes weaker and gas permeation and leakage even occur. Therefore, it can be concluded that the components made from Monel and stainless steel, especially those with thin walls, should not be heated to high temperatures in ultrahigh vacuum for a long time. The above phenomena are analyzed in detail theoretically and the proper and feasible application methods of the metallic materials are explored in device design and technological process control. These works are expected to contribute to the prolonging of the lifetimes of the satellites, and will lead to tremendous economic benefits.

Dealing with the genetic load in bacterial synthetic biology circuits: convergences with the Ohm's law.

Synthetic biology seeks to envision living cells as a matter of engineering. However, increasing evidence suggests that the genetic load imposed by the incorporation of synthetic devices in a living organism introduces a sort of unpredictability in the design process. As a result, individual part characterization is not enough to predict the behavior of designed circuits and thus, a costly trial-error process is eventually required. In this work, we provide a new theoretical framework for the predictive treatment of the genetic load. We mathematically and experimentally demonstrate that dependences among genes follow a quantitatively predictable behavior. Our theory predicts the observed reduction of the expression of a given synthetic gene when an extra genetic load is introduced in the circuit. The theory also explains that such dependence qualitatively differs when the extra load is added either by transcriptional or translational modifications. We finally show that the limitation of the cellular resources for gene expression leads to a mathematical formulation that converges to an expression analogous to the Ohm's law for electric circuits. Similitudes and divergences with this law are outlined. Our work provides a suitable framework with predictive character for the design process of complex genetic devices in synthetic biology.

Compliance of patients wearing an orthotic device or orthopedic shoes: A systematic review

Alongside the positive effects of use of orthotic devices for the lower extremities (ODLE) and orthopedic shoes, complaints and criticism by users possibly lead to non-compliance. The purpose is to determine the compliance of patients wearing an ODLE or orthopedic shoes and to describe the main reasons for using and not using. Different online databases were searched for articles about patients' compliance with regard to an ODLE or orthopedic shoes. A methodological quality control was conducted. Ten studies (1576 patients) were included. The data revealed between 6 and 80% not users. Several reasons for not using the orthotic device were described (e.g. pain, discomfort and cosmetically unacceptable). The high percentage of patients who are not wearing the prescribed orthotic devices leads to a high financial loss for society and a waste of therapeutic effort. These results should be taken into account during the design, construction and selection process of orthotic devices.

Establishing a Human Factors and Usability Center for Medical Devices in Brazil

This paper describes the main goals, motivation and challenges in developing Human Factors and Usability Engineering expertise to be applied to medical devices at a University in Brazil. With the advancement of medical instrumentation, it was necessary to develop studies to evaluate the variables that could affect the ability of people to use medical equipment properly. Advantages of using technological innovations in health care settings have been widely touted. However, many technologies designed to support patient treatment and diagnosis have been abandoned due to problems in their use and design. This has resulted in patient and user safety risks, an increase in healthcare complexity and dissatisfaction by end users. In Brazil, there is a lack in specialized centers that could investigate these problems. Also, there is a lack of knowledge of human factors methods that could help understand the causes of use errors and inform the medical device design process. Creating a Usability and Human Factors Lab for Medical Devices (and team) may increase health care safety by supporting usability studies on equipment while also educating and training students; this would benefit Brazilian industries, health care institutions and government agencies.

Putting medical devices in context: a systematic review of evidence on design targeting low-resource settings

Most medical devices are inaccessible to healthcare facilities in low-resource settings (LRSs), severely limiting medical care for a vast proportion of the world's population. This article characterises the process used for designing medical devices for LRSs and investigate how the context-of-use is integrated into the process. A systematic review of 64 papers was conducted to identify peer-reviewed studies of devices intended for LRSs. Using the biodesign process as an analytic framework, a qualitative meta-analysis was conducted. Findings show the studies predominantly describe the later stages of medical device design, whilst largely neglecting how knowledge of the context is considered. To support engineers and improve outcomes, it is imperative that an understanding of the context is integrated throughout the design and product development process. This article highlights this gap and hopes to stimulate research into how context can be better incorporated into the design process for medical devices targeting those populations most in need.

Статистический анализ и оптимизация параметров тех­нологии изготовления биполярного транзистора с изоли­рованным затвором

The use of computer simulation, design and optimization of power electronic devices formation technological processes can significantly reduce development time, improve the accuracy of calculations, choose the best options for implementation based on strict mathematical analysis. One of the most common power electronic devices is isolated gate bipolar transistor (IGBT), which combines the advantages of MOSFET and bipolar transistor. The achievement of high requirements for these devices is only possible by optimizing device design and manufacturing process parameters. Therefore important and necessary step in the modern cycle of IC design and manufacturing is to carry out the statistical analysis. Procedure of the IGBT threshold voltage optimization was realized. Through screening experiments according to the Plackett-Burman design the most important input parameters (factors) that have the greatest impact on the output characteristic was detected. The coefficients of the approximation polynomial adequately describing the relationship between the input parameters and investigated output characteristics ware determined. Using the calculated approximation polynomial, a series of multiple, in a cycle of Monte Carlo, calculations to determine the spread of threshold voltage values at selected ranges of input parameters deviation were carried out. Combinations of input process parameters values were determined randomly by a normal distribution within a given range of changes. The procedure of IGBT process parameters optimization consist a mathematical problem of determining the value range of the input significant structural and technological parameters providing the change of the IGBT threshold voltage in a given interval. The presented results demonstrate the effectiveness of the proposed optimization techniques.

Relating Mason number to Bingham number in magnetorheological fluids

Magnetorheological (MR) fluids are described using two nondimensional numbers, the Bingham and Mason numbers. The Mason number is the ratio of particle magnetic forces to viscous forces and describes the behavior of MR fluids at the microscopic, particle level scale. At the macroscopic, continuum scale, Bingham number is the ratio of yield stress to viscous stress, and describes the bulk motion of the fluid. If these two nondimensional numbers can be related, then microscopic models can be directly compared to macroscopic results. We show that if microscopic and macroscopic forces are linearly related, then Bingham and Mason number are inversely related, or, alternatively, that the product of the Bingham number and the Mason number is a constant. This relationship is experimentally validated based on measurements of apparent viscosity on a high shear rate, γ̇≈10000s-1, Searle cell rheometer. This relationship between Mason number and Bingham number is then used to analyze a Mason number based result, and is also used to inform the MR fluid device design process.

A co-modelling method for solving incompatibilities during co-design of mechatronic devices

The design process of mechatronic devices, which involves experts from different disciplines working together, has limited time and resource constraints. These experts normally have their own domain-specific designing methods and tools, which can lead to incompatibilities when one needs to work together using these those methods and tools. Having a proper framework which integrates different design tools is of interest, as such a framework can prevent incompatibilities between parts during the design process. In this paper, we propose our co-modelling methodology and co-simulation tools integration framework, which helps to maintain the domain specific properties of the model components during the co-design process of various mechatronic devices. To avoid expensive rework later in the design phase and even possible system failure, fault modelling and a layered structure with fault-tolerance mechanisms for the controller software are introduced. In the end, a practical mechatronic device is discussed to illustrate the methods and tools which are presented in this paper in details.

Dynamics of Microvalve Operations in Integrated Microfluidics

Pneumatic microvalves are widely used key components for automating liquid manipulation and flow control in microfluidics for more than one decade. Due to their robust operations and the ease of fabrication, tremendous microfluidic systems have been developed with the multiple microvalves for higher throughput and extended functionalities. Therefore, operation performance of the microvalves in the integrated microfluidic devices is crucial to the related applications, in fields such as micro-flows, cell analyses, drug discovery, and physical/chemical detections. It has been reported that operation performance of the microvalves are highly sensitive to the device configuration and pressurization scheme. This implies the further development of integrated microfluidics with a larger number of the valves may suffer the problems of undetermined microvalve behaviors during operations, which can become an unavoidable hurdle in the device design and optimization processes. Herein, we characterize responses of the individual microvalves for different operation configurations, e.g., membrane thicknesses and driving pressures. We investigate also the effects in microfluidics integrated with the more valves, through experiments, modeling and simulations. We show that dynamics of the microvalves is indeed influenced by the configurations, levels of design complexity and positions in the devices. Overall, taken dynamics of the microvalve responses into considerations, this work provides insights and guidelines for better designs of integrated microfluidics for the future applications requiring higher throughput and improved operation performance.

Managing the variability of biomechanical characteristics before the preliminary design stage of a medical device

The very high level of requirements for certification procedures often limit research and development departments to innovate using increments and iterations during the design process for medical devices (MD). Instead of this semi-empirical approach, a structured procedure, a breakthrough innovation should be used when designing an articular MD (prosthesis, implant). The search for concepts can be based on functional analysis and producing behavioural models of the joint in its natural state and/or equipped with the prosthesis. This paper shows how anatomical variables can be managed and integrated using a modular design approach.

Integration of Creativity Enhancement Tools in Medical Device Design Process

This paper aims at presenting the integration of different creativity enhancement tools, from C-K theory and TRIZ, in medical device design. After the description of the current development process, the paper focuses on the application of C-K mapping and TRIZ tools in a case study concerning the improvement of knee implants for total knee replacement - TKR - surgery. The analysis of this case study highlights that the synergy between TRIZ and C-K theory is possible. As a result, C-K theory represents a good way for structuring design reasoning mostly in the conceptual phases of product innovation and development and it may be also used to explore market information, while TRIZ is suitable for formulating and refining the design problem in a structured way.

Rear illumination monolithically integrated GaSb thermophotovoltaic devices grown on semi-insulating GaAs substrate

This paper presents the device design, modeling, materials growth, and device fabrication results of wafer scale monolithically integrated modules (MIMs) of series interconnected GaSb thermo-photovoltaic (TPV) cells grown on 50 mm diameter semi-insulating (SI) GaAs substrates. The feasibility of using GaSb epi-layers grown on SI GaAs for fabricating modules of photovoltaic (PV) cells connected in series for the conversion of low temperature heat radiating sources into electrical energy has been demonstrated. Device modeling shows that assuming an Shockley-Read-Hall recombination lifetime of 100 ns, in addition to intrinsic radiative and Auger recombination in GaSb, it is possible to design PV cells that when placed at sub-micron distance from a 900 °C radiating source are able to convert the heat into electrical energy at a power density of 1.5 to 3 W/cm2 using GaSb epi-layers grown on SI GaAs. The advantage of using SI GaAs is that it is possible to produce MIM modules of PV cells that can have output voltages of 6 V to 10 V decreasing the internal resistance of the PV cell. The device design and fabrication process presented here can be used for large area device arrays high efficiency solar photovoltaic cells employing other semiconductor materials for terrestrial and space applications with back-side illumination architecture.

Effect of Facial Material Softness and Applied Force on Face Mask Dead Volume, Face Mask Seal, and Inhaled Corticosteroid Delivery Through an Idealized Infant Replica

During the aerosol delivery device design and optimization process, in vitro lung dose (LD) measurements are often performed using soft face models, which may provide a more clinically relevant representation of face mask dead volume (MDV) and face mask seal (FMS) than hard face models. However, a comparison of MDV, FMS, and LD for hard and soft face models is lacking. Metal, silicone, and polyurethane represented hard, soft, and very soft facial materials, respectively. MDV was measured using a water displacement technique. FMS was measured using a valved holding chamber (VHC) flow rate technique. The LD of beclomethasone dipropionate (BDP) delivered via a 100-μg Qvar® pressurized metered dose inhaler with AeroChamber Plus® Flow-Vu® VHC and Small Mask, defined as that which passes through the nasal airways of the idealized infant geometry, was measured using a bias tidal flow system with a filter. MDV, FMS, and LD were measured at 1.5 lb and 3.5 lb of applied force. A mathematical model was used to predict LD based on experimental measurements of MDV and FMS. Experimental BDP LD measurements for ABS, silicone, and polyurethane at 1.5 lb were 0.9 (0.6) μg, 2.4 (1.9) μg, and 19.3 (0.9) μg, respectively. At 3.5 lb, the respective LD was 10.0 (1.5) μg, 13.8 (1.4) μg, and 14.2 (0.9) μg. Parametric analysis with the mathematical model showed that differences in FMS between face models had a greater impact on LD than differences in MDV. The use of soft face models resulted in higher LD than hard face models, with a greater difference at 1.5 lb than at 3.5 lb. A lack of a FMS led to decreased dose consistency; therefore, a sealant should be used when measuring LD with a hard ABS or soft silicone face model at 1.5 lb of applied force or less.

Study of Switching and Kirk Effects in InAlAs/InGaAs/InAlAs Double Heterojunction Bipolar Transistors

This paper investigates the two dominant but intertwined current blocking mechanisms of Switching and Kirk Effect in pure ternary InAlAs/InGaAs/InAlAs Double Heterojunction Bipolar Transistors (DHBTs). Molecular Beam Epitaxy (MBE) grown, lattice-matched samples have been investigated giving substantial experimental results and theoretical reasoning to explain the interplay between these two effects as the current density is increased up to and beyond the theoretical Kirk Effect limit for devices of emitter areas varying from 20x20 μm² to 1x5 μm². Pure ternary InAlAs/InGaAs/InAlAs DHBTs are ideally suited for such investigations because, unless corrective measures are taken, these devices suffer from appreciable current blocking effect due to their large conduction band discontinuity of 0.5 eV and thus facilitating the observation of the two different physical phenomena. This enhanced understanding of the interplay between the Kirk and Switching effect makes the DHBT device design and optimization process more effective and efficient.

Supporting safe walking for people with dementia: User participation in the development of new technology

Background Assistive technology is increasingly used to support people with dementia. One area attracting debate is the use of GPS systems. This paper presents the views of 12 people with dementia, 3 caregivers and 5 older people about GPS devices to promote safe walking. Methods Two focus groups were held, one in Scotland and one in England. Two researchers facilitated each group. Audio recordings were fully transcribed. Data were analysed using a qualitative, thematic approach. Results Walking and ‘getting out and about’ were common activities for participants and they reported that a GPS device would support them to go out independently with more confidence, or as their dementia progressed. Participants offered opinions on the design of the device and how it might be used in practice. GPS devices for people with dementia are considered useful by older people, people with dementia and family caregivers to support independence and increase self-confidence. Potential users of the device appear less concerned with the ethical issues relating to ‘tagging’ than those writing in academic journals and the media although they are interested in how the device might be used to promote independence rather than just as a safety precaution offering caregivers peace of mind. They also recommended that GPS devices be discreet rather than exacerbate any potential stigma. Conclusions Potential users of safe walking devices can see real potential to use the devices to increase independence while family carers see the benefits of reducing risk and addressing safety concerns. The inclusion of a user-engagement element to the device design process provided valuable information about how GPS devices might be used in the real world and specific ideas about different aspects of the device.