bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurement of Condensation Heat Transfer Coefficients in Microchannel Tubes
Authors: Garimella Srinivas , Bandhauer Todd M. 
Published: November 2021

Abstract
A technique for the measurement of condensation heat transfer coefficients in microchannels is reported. The high heat transfer coefficients and low mass flow rates in microchannels make it difficult to accurately measure these coefficients. The requirements for accurate heat duty measurement are in direct conflict with the requirements for deducing the heat transfer coefficients from measured temperatures and flow rates. In addition, measurement of local condensation heat transfer coefficients in small increments of quality is difficult to accomplish due to the low heat transfer rates for such quality changes. The present work reports a technique that addresses these requirements. The inlet and outlet qualities to a microchannel test section are measured through energy balances on a pre- and post-condenser. The test section is cooled using water at a high flow rate to ensure that the condensation side presents the governing thermal resistance. Heat exchange with a secondary cooling water stream at a much lower flow rate is used to obtain a large temperature difference, which is in turn used to measure the condensation duty. Local heat transfer coefficients are therefore measured in small increments for the entire saturated vapor-liquid region. This technique is demonstrated using a square microchannel geometry with a hydraulic diameter of 0.76 mm. Heat transfer coefficients for the condensation of refrigerant R134a in this geometry range from 2,110–10,640 W/m2–K over the mass flux range 150 &lt; G &lt; 750 kg/m2–s.
Measurement of the Temperature Field at the Tool-Chip Interface in Machining
Authors: Narayanan V. , Krishnamurthy K. , Chandrasekar S. , Farris T. N. , Madhavan V. 
Published: November 2021

Abstract
The measurement of the temperature field at the tool-chip interface in machining has been demonstrated. The key elements in the measurement technique are the use of an optically transparent sapphire tool, which has enabled direct images of the tool-chip contact area in the infra-red to be obtained at high spatial and temporal resolution; and radiation intensity measurements in two wavelength windows which have enabled the temperature field to be accurately derived from these intensity values. The principal characteristics of the temperature field such as the variation of temperature with position along the interface and the location of the region of highest temperature are identified. The implications of this measurement to our understanding of the tribology of the tool-chip interface and machining process models are briefly discussed.
Microstructure-Level Modeling of Ductile Iron Machining
Authors: Chuzhoy L. , DeVor R. E. , Kapoor S. G. , Bammann D. J. 
Published: November 2021

Abstract
A microstructure-level model for simulation of machining of cast irons using the finite element method is presented. The model explicitly combines ferritic and pearlitic grains with graphite nodules to produce the ductile iron structure. The behaviors of pearlite, ferrite, and graphite are captured individually using an internal state variable model for the material model. The behavior of each phase is dependent on strain, strain rate, temperature, and amount of damage. Extensive experimentation was conducted to characterize material strain rate and temperature dependency of both ferrite and pearlite. The model is applied to orthogonal machining of ductile iron. The simulation results demonstrate the feasibility of successfully capturing influence of microstructure on machinability and part performance. The stress, strain, temperature, and damage results obtained from the model are found to correlate well with experimental results found in the literature. Furthermore, the model is capable of handling various microstructures in other heterogeneous materials such as steels.
A Model-Based Prediction Approach to Understanding Tool Wear
Authors: Kim W. , Wong T. , Kwon P. 
Published: November 2021

Abstract
Since the development of Taylor’s wear equation in the early 1900s, empirical approaches to tool wear have been extensively used by industries. However, as many types of work materials and cutting tools have emerged, developing the empirical equation for each combination of work material and cutting tool is too costly and time-consuming. In this paper, we present a promising new model-based approach, where the developed model can be directly extended to other work materials and cutting tools. However, when machining pearlitic steels at high cutting speed, phase transformation restricts the model’s applicability. With phase transformation, the associated flank wear does not follow the model’s predictions. Evidently, the abrasive action of cementite is suppressed as the cementite phase in pearlitic microstructure transforms into austenite. This paper summarizes and reevaluates our previous experimental results in order to develop a model-based approach to understanding and predicting tool wear.
Deformation During High Pressure and Pressure Sequence Hydroforming of Tubes
Authors: Orban H. , Hu S. J. , Duncan J. L. , Morphy Gary 
Published: November 2021

Abstract
Hydroforming is a process used to manufacture tubular sections from circular tubes. Two systems for hydroforming are mainly used, high pressure hydroforming (HPH), and pressure sequence hydroforming (PSH). In this paper, an energy approach is used to calculate the compressive forces developed in the tube wall during deformation in PSH. The pressure required to prevent buckling of the tube wall is estimated based on a two dimensional buckling model. The differences in the mechanics of deformations between HPH and PSH are explained. The advantages and limitations of both systems are also summarized.
Enhancement of Coil Stiffness Using a Cardboard Core
Authors: Li Shunping , Cao Jian 
Published: November 2021

Abstract
Problems of excessive coil deformation after winding will present difficulties in later material handling. Sheet material with a lower stiffness is more likely to deform than solid sheet coil. In this paper, numerical and analytical methods are used to study the factors causing this problem. The results can be used to estimate the requirement of the supporting core material to prevent this excessive coil deformation.
Performance Characterization of Micromachined Tunneling Infrared Detectors
Authors: Ajakaiye Olaleye , Shin Choongsoo , Grade John , Kenny Thomas W. 
Published: November 2021

Abstract
The individual assembly of early generation tunneling infrared detectors required time and skill that were incompatible with high volume production and resulted in large variations in key device operating parameters. The parts of the sensor were glued together and the yield was poor. This paper describes the first successful wafer scale production of micromachined tunneling infrared detectors. The detectors produced with this process feature performance consistent with the best tunneling sensors developed so far and are suitable for use as state-of-the-art uncooled infrared detectors. The noise in these detectors is measured to be below 30 μV/rtHz with a corresponding noise equivalent power (NEP) of less than 10−8 W/rtHz.
Magnetically Actuated, Circular Diaphragm Pumps Fabricated With Low-Temperature, Co-Fired Ceramic Tapes and Kapton Polyimide Films: Experiments and Theory
Authors: Kim Moon , Ananthasuresh G. K. , Bau Haim H. 
Published: November 2021

Abstract
Magnetically actuated diaphragm pumps were fabricated with low temperature co-fired ceramic (LTCC) tapes and Kapton polyimide film. The pumps consisted of a chamber machined in a LTCC substrate. The chamber was covered either on one or both sides with Kapton diaphragms on which copper coils were patterned. The diaphragms were actuated by passing electric current through the coils in the presence of permanent magnets. Passive Kapton flap valves were used to direct fluid flow into and out of the chamber. The first design consisted of a single, circular diaphragm pump. In the second design, two circular diaphragms were used. The two diaphragms are deflected into and out of the pressure chamber simultaneously. Flow rates of up to 7 mL/min were measured. The static response of a circular diaphragm subjected to magnetic forces was computed using the finite element method (FEM). The effect of the copper coils on diaphragm stiffness was accounted for. The design parameters (the number of windings and the size and location of the magnet) needed to maximize the volumetric displacement were determined. At relatively high currents, the coils heated up significantly and caused the pump’s performance to deteriorate.
A CMOS-MEMS Micromirror With Large Out-of-Plane Actuation
Authors: Xie Huikai , Pan Yingtian , Fedder Gary K. 
Published: November 2021

Abstract
This paper reports a high-aspect-ratio, silicon-based vertical comb drive used to actuate a micromirror. The large displacement is achieved by the curled-up comb drives. This high-aspect-ratio vertical comb drive uses the vertical capacitance gradient of the sidewall capacitor existing between comb fingers. The electrical isolation is realized by using the undercut of the deep Si etch. The 1 mm by 1 mm micromirror is made of an approximately 40 μm-thick single-crystal silicon membrane with aluminum coated on the surface. The mirror has a peak-to-peak curling of 0.5 μm. The mechanical rotation angle of the mirror is ±5°. The fabrication process is compatible with standard CMOS processes, and there is no need for wafer bonding and accurate front-to-backside alignment. Such capability has potential applications in optical switches, optical scanners, interferometric systems, and vibratory gyroscopes.
Development and Testing of a Planar, Silicon Mini-Capillary Pumped Loop
Authors: Pettigrew Kenneth , Smith Brian , Yerkes Kirk , Gamlen Carol , Liepmann Dorian 
Published: November 2021

Abstract
A planar, silicon mini capillary pumped loop (CPL) was designed, built, and tested using recent MEMS technology to provide integral cooling and temperature control for electronics. This design featured three silicon fusion bonded wafers incorporating an evaporator, condenser, liquid line and vapor line, all of which were dry plasma etched. Grooves were etched in the condenser and evaporator to provide passive capillary pumping. An insulated gate bipolar transistor (IGBT) was bonded to the evaporator region of the CPL and an external reservoir attached to a port hole in the finished device. The CPL was then filled with a working fluid of water. A calorimeter was attached via epoxy above the condenser to control condenser temperature and monitor heat removal. The mini-CPL was operated with an input heat load ranging from 3 to 10 W resulting in the junction temperature of the IGBT being reduced approximately 15 C from that of a solid SI substrate. This mini-CPL also performed as a thermal diode, turning on or off depending on the reservoir temperature. Work is in progress to understand the dynamics observed in the CPL as well as increase the CPL’s performance to its full potential.
Actuation of MEMS by Light: An Optical Actuator
Authors: Sulfridge Marc , Saif Taher , Miller Norman , O’Hara Keith 
Published: November 2021

Abstract
This paper presents experimental evidence that MEMS devices may be manipulated using beams of light. Light possesses momentum, and hence it imparts a force equal to 2W/c when perfectly reflected by a surface. Here W is the total power of the reflected light, and c is the speed of light. The radiation pressure of light can be quite significant to MEMS devices. This actuation method is demonstrated, both in air and in vacuum, by switching the state of a bi-stable MEMS device. The associated heat transfer model is also presented.
Stress Relaxation of Gold/Polysilicon Layered MEMS Microstructures Subjected to Thermal Loading
Authors: Zhang Yanhang , Dunn Martin L. 
Published: November 2021

Abstract
We study both experimentally and theoretically the stress relaxation behavior of a series of gold/polysilicon MEMS microstructures fabricated by the MUMPs surface micromachining process and subjected to thermal loading. We measured, using an interferometric microscope with a custom-built temperature chamber, full field deformed shapes (and from these determined the average curvatures in x and y directions) of gold (0.5 μm thick)/polysilicon (1.5 or 3.5 μm thick) beam and plate microstructures. The microstructures are initially thermal cycled between room temperature and 190°C to stabilize the gold microstructure. After the initial thermal cycle, the microstructures are cooled from 190 °C to 120 °C and held at 120°C for about six weeks. During the isothermal hold, stress relaxation is observed in all of the microstructures. Both material and structural issues contributed to the observed deformation response. The coupling of the two was apparent in plate microstructures where the initial cooling caused them to buckle, but the stress relaxation then caused them to substantially unbuckle. We attempted to model the stress relaxation process by assuming simple power-law creep in the gold ε ˙ = A σ n , and assuming that the polysilicon did not relax at the modest temperature of 120 °C. We found that with such a simple model we could not obtain self-consistent results among all measurements. However, with a stress component of n = 5, good agreement was obtained among beam and plate microstructures using a value of A that depended on the microstructure thickness. The reasons for this are unclear presently, but these results resonate with similar studies of thin films on thick substrates in microelectronics contexts.
Resistance of Liquid Metal Droplets Against Actuation on Microstructured Surfaces
Authors: Shen Wenjiang , Kim Joonwon , Kim Chang-Jin “CJ” 
Published: November 2021

Abstract
Liquid metal droplet can be used as contact and moving part in a microswitch system for such application areas as space electronics. In order to build clear knowledge about the behavior of liquid metal droplet under electrostatic actuation, the contact properties of the droplet on structured surface are investigated in this paper. Forces needed to slide or detach a liquid metal droplet on microstructured surface are theoretically analyzed. Micropositionor and a high-resolution goniometer are used to build up testing setup to experimentally evaluate sliding and detaching of the liquid metal droplet. Experimental results show that the physical modification (i.e., microstracturing) of surface can greatly reduce the adhesion between liquid metal droplet and solid surface and ease its actuation.
Mechanical Characterization and Controlled Manipulation of Micro Objects Using Vision-Based Techniques and Compliant Devices
Authors: Wang Xiaoye , Ostrowski James P. , Ananthasuresh G. K. 
Published: November 2021

Abstract
Stiffness characterization and mechanical manipulation of rigid or flexible micro objects using compliant devices are investigated in this paper. Compliant devices are themselves elastically deformable objects. By using the material properties, geometry, and measured deformations of the compliant devices, the force and deflection of the manipulated object are computed using geometrically nonlinear mechanics formulations. Thus, the stiffness of any given object is characterized. Since the input and output points might be occluded, we have developed an alternate approach where displacement measurement at other points can be used to estimate the forces at input and output points. This new technique also helps reduce the effect of errors in optical capturing of deformations in the computation of forces. By virtue of this vision-based force measurement, we can apply controlled force on the objects, which is a very useful feature in micro assembly and manipulation where excessive force might damage the object. Additionally, we demonstrate manipulation with compliant devices utilizing vision-guided position and force control. Illustrative examples at micro and macro size scales are included.
Selective Chemical Liquid Deposition for Fabrication of Mini-Structures and Microsystems
Authors: Zhou Jack G. , Wang Feng 
Published: November 2021

Abstract
Most technologies used in fabrication of MEMS involve very sophisticated and expensive processes, which limit the application of MEMS greatly. This paper presents our research on a new manufacturing technology named Selective Chemical Liquid Deposition for Mini-structures and Microsystems SCLD-MSMS. In SCLD-MEMS, small droplets of solution or liquid reactant are ejected from a nozzle at room temperature, the droplets decompose or react with each other after impinging upon a hot substrate, the reacted solid products will then deposit on the substrate. By controlling the droplet size, the flow rate, the motion of the nozzle, and the temperature of the substrate, as well as other process parameters, a desired 3-D microstructure of deposited material can be formed through layer-by-layer scanning technique. The working principle and some experiment results are discussed in this paper.
A Review of Laminar Single-Phase Flow in Microchannels
Authors: Papautsky Ian , Ameel Tim , Frazier A. Bruno 
Published: November 2021

Abstract
Microfluidics plays a major role in the development of many innovative research activities aimed at the development of miniaturized devices and systems, and new applications related to microscale handling of fluids. As the field of microfluidics continues to grow, it is becoming increasingly important to understand the mechanisms and fundamental differences involved in microscale fluid flow. This paper presents a summary of the experimental research efforts in the area of microscale single-phase internal fluid flow and discusses issues associated with investigating microscale flows. While the currently available experimental data indicate the presence of microscale phenomena, they do not unequivocally identify the effects. There is a clear need for additional experimental investigations.
Operational Limits of Suspension Flows Through Sudden Contractions
Authors: Stoeber Boris , Español Eddie , Liepmann Dorian 
Published: November 2021

Abstract
In many microfluidic MEMS (Micro Electromechanical Systems) especially in μTAS (micro Total Analysis Systems) suspensions of small particles are transported from relatively large chambers into small channels. The sudden contractions at the entrance to these channels are critical flow regions where high shear occurs in the fluid. Even very small particles at low concentrations have been observed to accumulate in these regions where they clog the channel inlet occasionally after a short period of time. The operational limitations for three-dimensional suspension flows are examined using dimensional analysis. Thus empirical relations based upon experimental results can be established between the parameters involved in this fluid mechanical problem such as shear rate, particle size and concentration, size and number of sudden contractions, and the time scale of clogging.
Liquid Transport Properties in Sub-Micron Channel Flows
Authors: Westin K. Johan A. , Breuer Kenneth S. , Choi Chang-Hwan , Huang Peter , Cao Zhiqiang , Caswell Bruce , Richardson Peter D. , Sibulkin Merwin 
Published: November 2021

Abstract
An experimental set-up for pressure driven liquid flow through microchannels have been designed and tested. The flow rate is determined by tracking the free liquid surface in a precision bore hole using a laser distance meter. Measurements of the flow rate through silicon microchannels with a height of less than 0.9 μm show good results for Newtonian fluids (silicon oil, ethanol) at flow rates as low as 0.2 nl/s. The experimental results are also in very good agreement with predictions based on laminar channel flow using no-slip boundary conditions, indicating that standard macroscopic assumptions are still valid for these fluids under these conditions. However, experiments with aqueous solutions show anomalies in the form of unexpectedly low flow rates and time dependent variations. Possible explanations to these observations are discussed.
Ratcheting Electrophoresis Microchip (REM) for Programmable Transport and Separation of Macromolecules
Authors: Ohara T. , Majumdar A. 
Published: November 2021

Abstract
This paper introduces the concept of a ratcheting electrophoresis microchip (REM), a microfluidic device for electrophoretic separation of macromolecules such as DNA and proteins in aqueous solution using low applied voltages (∼ 1 V). The device consists of several thousands of parallel linear electrodes with a constant pitch of about 10 μm. A spatial saw-tooth like potential distribution generated by the electrode array causes local electrophoretic migration of charged molecules between adjacent electrodes. By cycling the potential distribution in a certain pattern, the spatio-temporal electrophoretic ratchet can be used to separate and manipulate macromolecules at speeds much faster than thermal ratchets or more traditional techniques such as capillary or gel electrophoresis. This paper describes results of two simulations: First, using a simple one-dimensional potential distribution for the ratchet, the basic device function is examined using a probabilistic approach that simulates the interplay between electrophoretic mobility and molecular diffusion. The results suggest that the REM can function as a molecular filter through which only molecules having mobility larger than a threshold can pass. The REM can also be programmed to separate molecules to create a molecular profile, much like conventional electrophoresis. Second, two-dimensional stochastic simulations based on molecular diffusion and transient Debye screening by mobile ions are used to demonstrate the feasibility of the REM. The results suggest that biomolecular separation can indeed be achieved within time and length scales much shorter than capillary and gel electrophoresis.
High-Impulse Digital Microthrusters Using Low-Boiling-Temperature Liquid Propellant With High-Viscosity Fluid Plug
Authors: Kang Tae Goo , Kim Sang Wook , Cho Young-Ho 
Published: November 2021

Abstract
A high-impulse, low-power, digital microthruster has been developed using low-boiling-temperature liquid propellant with high-viscosity fluid plug. The low-boiling-temperature propellant is used for reducing the electrical input power required for blast pressure build-up, while the high-viscosity fluid plug is intended to withhold the propellant pressure for the high-impluse blast. The three-layer microthruster has been fabricated by surface micromachining as well as bulk micromachining in the size of 7mmx13mmx1.5mm. At the continuous operation mode, the maximum output impulse bit of 6.4 × 10−8 N·sec is obtained for the fabricated microthruster using perfluoro normal hexane (FC72) propellant and oil plug.
Zinc Bonding for MEMS Packaging at the Wafer-Level
Authors: Lee Ki Bang , Lin Liwei 
Published: November 2021

Abstract
A new bonding process for MEMS packaging at the wafer-level using electroplated nickel and zinc is demonstrated. Package with the electroplated zinc solder and nickel support for forming the cavity for MEMS has been presented and demonstrated. A set of wafers is bonded at the temperature of 425°C and under the pressure of 1000N/ m2 and examined to estimate the bonding strength of bonded wafer. The bonding strength between zinc and gold is comparable to the fracture of toughness silicon. Bonding mechanism and fabrication process has been discussed.