Showing papers on "Microheater published in 2008"

A Nano Initiator Realized by Integrating Al/CuO-Based Nanoenergetic Materials With a Au/Pt/Cr Microheater

Abstract: A nano initiator is developed by integrating Al/CuO-based nanoenergetic materials with a Au/Pt/Cr thin-film microheater realized onto a glass substrate. It is fabricated by using standard microsystem techniques that allow batch fabrication and high level of integration and reliability. The nano initiator is characterized by open-air combustion testing with an ignition success rate of 98%. The ejected combustion flame is seen clearly with a potential exceeding 2000 . The ignition power, ignition delay, and ignition energy are 1.16 W, 0.1-0.6 ms, and 0.12-0.70 mJ, respectively. The energy output is calculated to be around 60 mJ.

Microhotplates with TiN heaters

Abstract: Titanium nitride (TiN) has been investigated as a heater material for microhotplates and microreactors. TiN is available in many CMOS processes, unlike many other microheater materials. In addition, TiN has a very high melting point (2950 ◦C) meaning that it is stable up to higher temperatures than platinum (Pt) and polysilicon. For the first time, TiN is tested inside a conventional membrane of LPCVD silicon nitride (SiN). Two types of sputtered TiN are considered: high stress and low stress. Their performance is compared with that of e-beam evaporated Pt. The maximum average temperature of TiN heaters is 11% higher than those of Pt, and reaches over 700 ◦C. Failure of the TiN heaters is due to rupture of the membrane. Failure of the Pt heater is due to electro-stress migration. For high-stress TiN, the temperature coefficient of resistance is almost constant and close to that of Pt, making the material very suitable for temperature sensing. In the case of low-stress TiN the temperature coefficient of resistance (TCR) becomes nonlinear and changes sign. The large differences between the materials are explained by the grain structure. The different grain structures are related to the sputtering parameters according to the Thornton model.

Modeling and Experimental Identification of Silicon Microheater Dynamics: A Systems Approach

Abstract: Microfabricated silicon cantilevers with integrated heating elements are powerful tools for manipulation and interrogation at the nanoscale. They can be used for highly localized heating of surfaces and also serve as electrothermal probes such as topography and position sensors. A thorough understanding of the dynamics of these heating elements is essential for an effective design and operation of such devices. In this paper, we present a tractable feedback model that captures the dynamics of these microheaters. The operator model separates the thermal and the electrical response of the microheater into two operators, with a linear dynamic operator mapping the applied electrical power to the heater temperature and a second nonlinear but memoryless operator mapping the heater temperature to the electrical resistance. We present experimental results that show the identification of a write heater used in probe-based thermomechanical data storage and the accurate synthesis of arbitrary temperature profiles. In the application of microheaters as electrothermal probes, the signals being measured are believed to perturb the thermal system. Therefore, an extension of our model is presented to analyze the response to this perturbation. The extended model is used to identify and forecast the performance of electrothermal sensors, such as the read heater in probe-based data storage. Also presented are results on thermal position sensors, in which microheaters are employed as nanoscale position sensors for a MEMS-based microscanner.

Design and integration of an all-in-one biomicrofluidic chip.

Abstract: We demonstrate a highly integrated microfluidic chip with the function of DNA amplification. The integrated chip combines giant electrorheological-fluid actuated micromixer and micropump with a microheater array, all formed using soft lithography. Internal functional components are based on polydimethylsiloxane (PDMS) and silver/carbon black-PDMS composites. The system has the advantages of small size with a high degree of integration, high polymerase chain reaction efficiency, digital control and simple fabrication at low cost. This integration approach shows promise for a broad range of applications in chemical synthesis and biological sensing/analysis, as different components can be combined to target desired functionalities, with flexible designs of different microchips easily realizable through soft lithography.

The design, fabrication and characterization of a silicon microheater for an integrated MEMS gas preconcentrator

Abstract: We report the design and fabrication of a microheater unit as a key component of an integrated micro gas preconcentrator that has an ultra-small preconcentrator volume (<0.25 µL) and microvalves for fast injection speeds (<1 ms). Monolithic integration of the microvalves into the microheater of the preconcentrator gives rise to challenges in designing the microheater and implementing thermal isolation for low power and energy consumption. A preconcentrator chamber, 3.5 × 1.5 mm2 in planform area and 40 µm deep, was built in the device layer of a silicon-on-insulator wafer and filled with an array of microposts with a preconcentrator volume of 0.2–0.25 µL. Different generations of the microheaters and their mating dies were fabricated to show the effects of thermal isolation and thermal mass of the system on the performance of the heater. The microheater assembly with the least thermal mass and most thermal isolation can reach 300 °C in 100 ms with 12.3 W of power and is expected to consume less than 2 J during the operation of each preconcentration cycle.

A Novel Two-Axis CMOS Accelerometer Based on Thermal Convection

Abstract: Accelerometers based on thermal convection use a tiny bubble of heated air and pairs of temperature sensors hermetically sealed inside the sensor package cavity. In this paper, we successfully design and fabricate a novel thermal-bubble-based micromachined accelerometer with the advantages of minimized solid thermal conductance and higher sensitivity. The proposed accelerometer consists of a microheater and two pairs of thermopiles floating over an etched cavity and is constructed by our proposed microlink structure. Two-dimensional acceleration detection is easily realized using the microlink structure, and it can be applied to the technology of inclinometers, anemometers, and flowmeters. The heater and thermopiles are connected by netlike microlink structures, which enhance the structure and greatly reduce the solid heat flow from the heater to the hot junctions of the thermopiles. The samples are fabricated by the TSMC 0.35-mum 2P4M CMOS process, which has been provided by the national chip implementation center (CIC). Our design has proved to be applicable for commercial batch production with outstanding strong structures and uniform quality. We measure the output signal by inclining the sensor to evaluate the performance of this accelerometer. The best sensitivity of 22 muV/g was obtained from acceleration versus output voltage under several experimental conditions.

A Disposable Plastic-Silicon Micro PCR Chip Using Flexible Printed Circuit Board Protocols and Its Application to Genomic DNA Amplification

Abstract: This paper describes a novel disposable and portable plastic-silicon polymerase chain reaction (PCR) system using microfabrication technologies for the realization of miniaturized nucleic acid analyses. The system consists of a polyimide-based film microheating system, embedding with a microheater and a temperature sensor made entirely with flexible printed circuit board (FPCB) process protocols, and a bulk-micromachined silicon reaction chamber. Reduction of the thermal mass by employing a 25 mum-thick polyimide film substrate, which has chemical and thermal resistance suitable for photolithography processes, and integration of a temperature sensor as well as a heater on the film facilitates rapid and precise temperature control. The microfabricated PCR chip demonstrated precise heat control and rapid thermal response in the chip. In addition, the chip successfully amplified a genomic DNA template (breast cancer suppressor gene, BRCA 1 127 base pairs), extracted from the human whole blood containing approximately 100 copies in a 3 muL-volume chamber within 18 min. Thus, it is applicable to a portable system for precise, fast, efficient and cost-effective nucleic analysis, and can be utilized with microscale biochemical analysis and sensing systems as well.

Gallium arsenide suspended microheater for MEMS sensor arrays

Abstract: This work describes the design, simulation, fabrication and characterization of a TiN/Pt microheater prepared on a GaAs micromechanical structure as a prospective device for micro-electro-mechanical system (MEMS) sensor arrays. Electro-thermal simulation was employed to verify the properties of the designed microstructure, which confirmed achievement of the operating temperatures in the range from 470 to 600 K with a heating power less than 25 mW. The average temperature gradient in the active area does not exceed 0.6 K/μm. Fabrication of GaAs suspended membranes was demonstrated, realized in two steps by combination of surface and bulk micromachining. Development and characterization of a microheater on a GaAs membrane is described. The mechanical stability of the heated multilayer membrane structure was tested and satisfactory mechanical stability of the hotplate was confirmed. The power consumption at an operating temperature of approximately 550 K is about 30 mW which is in good agreement with the value of about 22 mW obtained from electro-thermal simulation. The achieved thermal resistance value is 8.43 K/mW.

Fabrication of an integrated microfluidic device based on a heat-sensitive poly(N-isopropylacrylamide) polymer and micromachining protocols for programmed bio-molecular patterning

Abstract: Due to their broad application in biochemical analysis, the miniaturized and integrated microfluidic devices which can give a biochemically active phase for diagnostic capabilities on single chips are very important in contemporary research. Here, we present an integrated microfluidic device applicable to sample preparation, like the controlled patterning of target biomolecules, like proteins or cells, with a smart polymer-modified temperature-addressable microelectrode that is thermally switched between hydrophilic and hydrophobic states. The device is composed of a bulk-micromachined Si device and a hot-cast poly(dimethyl siloxane) (PDMS) device. The microelectrode a array has been integrated into a micro-hot plate having an embedded microheater and temperature sensors on 2-μm thick silicon oxide/silicon nitride/silicon oxide (O/N/O) stacking layer, and is designed to adsorb and release biomolecules with low power consumption and rapidness in a microfluidic chamber. To provide the heat-responsive activity to the microelectrode surface, the electrode surface was modified with poly(N-isopropylacrylamide) (PNIPAAm), which shows a rapidly reversible hydrophilic-to-hydrophobic transition in response to temperature changes. In this study, design, fabrication and its characterization of the microfluidic device with NHS PNIPAAm surface modifications on the dendrimer monolayer conjugated microelectrode were carried out. And then, the synthesis and the confirmation of surface modification with the smart polymer by grazing FT-IR spectroscopy and contact angle analyzer were demonstrated. The microfluidic devices would be directly applicable to a portable battery-powered biochemical system.

A Micromachined Chip-to-Board Interconnect System Using Electroplating Bonding Technology

Abstract: We demonstrate a micromachined flexible chip-to-board chip interconnect structure for a chip scale package. Micromachined flexible interconnects enable robust operation in high thermal cycling environments, even for high pinout chips due to the flexible interconnect ability to absorb thermal expansion strain. The interconnects on the chip-side and printed wiring board (PWB)-side are united by electroplating bonding technology, a direct bonding technology resulting in solder-free, underfill-free, low temperature joining by means of copper (Cu) electroplating. Over 200 surface micromachined interconnects, which have a thermal relief geometry, are radially arranged on 11 cm substrates. A chip surrogate consisting of glass with integrated platinum (Pt) microheaters mimics a real electronic device under varying thermal loads. The integrated microheaters can simultaneously test mechanical and electrical performance of the interconnects by generation of on-chip temperatures up to 150 C. Lateral and vertical displacement of the interconnects in the thermal environment are measured and simulated. A mechanical reliability test of the chip scale package is successfully performed for 5000 cycles with thermal cycles of 5 min between 40 C to 147 C. No failures were observed during this period.

Polymer Channel Chips as Versatile Tools in Microchemistry

Abstract: The paper describes the fabrication and chemical applications of polymer microchannel chips, with special reference to in situ observations of the chemical/physical processes occurring in polystyrene microchannel chips, including those in microchannel-microelectrode/microheater chips. On the basis of absorption/fluorescence microspectroscopy and microelectrochemistry techniques, we show some characteristic features of liquid/liquid extraction, electrochemical responses, and photochemical/electrochemical/thermal synthetic reactions in microchannel chips.

Study on metal membrane temperature sensor and microheater for pcr chip

Abstract: The development of PCR chip shortens the reaction time of DNA amplification, reduces the bulk of reaction reagents; therefore, it is widely applied to biomedicine and other related fields. Since PCR reaction is completed through three different precise temperature zones periodically, the sensitivity of temperature measurement and the heating property of the metal membrane must be highly regarded. In this paper, three kinds of membranes, Ni, Pt, and Ni–Cr, were fabricated on silicon substrates; their resistance–temperature characteristics and heating properties are discussed. The results show that Ni and Pt films have good linear resistance–temperature relationship; the heating property of Pt film is superior to that of Ni–Cr film. The PCR chip with Pt film microheater can reach 150°C in a short time with 25 V voltage.

Wettability Effect on Flow Boiling in an MEMS-Based Single Glass Microchannel

Abstract: Many studies have investigated boiling heat transfer in microchannels; however, such phenomena are not yet fully understood, and conflicting results have been reported. There are many important parameters that govern behavior in microsystems, including channel shape, roughness, and choice of material. One potentially important parameter is hydrophobicity of the microchannel surface, as interfacial forces play an increasing role at microscales. We developed a new method of fabricating a single glass rectangular microchannel and microheater using the MEMS (Micro-Electro-Mechanical System) fabrication technique. The glass was used as a hydrophilic surface, and a self-assembled monolayer was coated with OTS (Octadecyl-Trichloro-Silane) to obtain a hydrophobic surface. We conducted an experiment of boiling heat transfer in a microchannel using two surfaces of contrasting hydrophobicity. The resulting flow was observed using a long-distance microscope and a high-speed camera. This approach enables a qualitative analysis of the hydrophobicity effect on the flow regime.Copyright © 2008 by ASME

New type thin film vacuum sensor using the short circuit seebeck-current detection type thermocouple

Abstract: We have proposed the thin film vacuum sensor that has a cantilever structure with new temperature difference sensors of the short circuit Seebeck-current detection type thermocouple in order to get higher sensitivity in the higher vacuum range. Temperature difference, which should be zero under the higher vacuum, between microheater and thermally isolated heading area from the microheater is measured under the vacuum pressure. Even a little temperature difference in our new sensor can be measured in very lower vacuum pressure range by the signal amplification than that of the traditional Pirani vacuum sensor. In our experiments, the short circuit Seebeck-current detection type thermocouple is used to measure the very small temperature difference. Measurement of very wide vacuum pressure range between 105 - 10-2 Pa is achieved by the prototype sensor.

열민감성 공액고분자를 이용한 미세유동칩 내의 온도 측정

Abstract: Microfluidic chips have been frequently utilized to perform biochemical analysis, like cell culture, cell-based drug screening, biomolecule synthesis, and etc, because they reduce the consumptions of analytes and reagents and automate multi-step analysis processes. It is often critical to monitor temperature in a microchannel for the analysis in order to control a reaction rate of biomolecules. We propose a novel method to monitor a temperature change in a microchannel flow by using polydiacetylene (PDA), a conjugated polymer, that has a unique property to transform its color from visible blue to fluorescent red by thermal stress. We inject PDA sensors of the form of a droplet into the microchannel with a microheater on the bottom. Preliminary results show that the florescence intensity of a PDA sensor droplets varies with the temperature.

폴리다이아세틸렌을 이용한 미세유동칩 내의 온도 측정

Abstract: Microfluidic chips have been frequently utilized to perform biochemical analysis, like cell culture, because they reduce the consumptions of analytes and reagents and automate multi-step analysis processes. It is often critical to monitor temperature in a microchannel for the analyses in order to control a reaction condition of bio or chemical molecules. We propose a novel method to monitor temperature of a microchannel flow by using polydiacetylene (PDA), a conjugated polymer, that has a unique property to transform its color from visible blue to fluorescent red by thermal stress. We inject PDA sensor droplets generated by hydrodynamic instability into a microchannel with a microheater incorporated on the channel bottom. Also, we change the channel temperature by providing the different electric power to the microheater. The results show that the florescence intensity of PDA sensor droplets linearly increases in response to the flow temperature increase within a certain range.

Development and characterization of a microheater array device for real-time DNA mutation detection

Abstract: DNA analysis, specifically single nucleotide polymorphism (SNP) detection, is becoming increasingly important in rapid diagnostics and disease detection. Temperature is often controlled to help speed reaction rates and perform melting of hybridized oligonucleotides. The difference in melting temperatures, Tm, between wild-type and SNP sequences, respectively, to a given probe oligonucleotide, is indicative of the specificity of the reaction. We have characterized Tm's in solution and on a solid substrate of three sequences from known mutations associated with Cystic Fibrosis. Taking advantage of Tm differences, a microheater array device was designed to enable individual temperature control of up to 18 specific hybridization events. The device was fabricated at Sandia National Laboratories using surface micromachining techniques. The microheaters have been characterized using an IR camera at Sandia and show individual temperature control with minimal thermal cross talk. Development of the device as a real-time DNA detection platform, including surface chemistry and associated microfluidics, is described.

Micro bio chip for sample pre-treatment and dna purification method using the same

Abstract: PURPOSE: A microbiochip for pretreatment of sample and a method for extracting DNA using the same are provided to reduce the amount of sample, time, cost, and labor. CONSTITUTION: A micro biochip(100) for pretreatment of a sample comprises: a heating unit which regulates temperature for efficient experiment; a PDMS(polydimethylsiloxane) chip(130) having a channel(132) with a micro-filter for extracting pure DNA; and thin film glass chip(140). The heating unit comprises a glass chip(160) placed at the lower part of the thin film glass chip, micro heater, and temperature sensor(180). A method for extracting DNA using the micro biochip comprise: a step of injecting microbead to the channel in reaction bath; a step of filtering microbead in a micropillar; a step of injecting sample cells to the channel; a step of heating the sample cells with the microheater to break cell wall; and a step of extracting DNA.

On-Chip Temperature Sensing and Control for Cell Immobilization and Culture System

Abstract: This paper presents a temperature sensing and controlling microfluid chip for cell immobilization using a thermo-sensitive hydrogel (PNIPAAm). The ITO (Indium Tin Oxide) microheaters fabricated by micromachining technology, perform heating of the solution of cell, PNIPAAm and Calcein-AM (fluorescent dye) in microchannels. It is important to note that a thick gel formation cause to block the observation of culturing cells due to the autofluorescence of gel which reduce the S/N ratio. For the present study, we are targeting to fabricate a suspended micro-bridge above a microheater to limit the height of gel to form "thin and transparent gel layer" above the heater. The research was focused on controlling of gel thickness which eliminated unnecessary interferences of autofluorescence of gel in the observation by the inverted microscope, and a better S/N ratio can be obtained than the conventional observation with uncontrolled gel thickness. All the heating and a suspended biocompatible micro-bridge were integrated on a chip, in which yeast cells immobilization can be performed by the gelation of the PNIPAAm solution.

A Nanostructured Thermosensitive Smart Surface With Integrated Microheater for Wettability Control

Abstract: This paper describes the design and fabrication of a switchable thermosensitive polymer with an integrated microheater as a smart surface platform for wettabilty control. The thermoresponsive surface is synthesized on a glass substrate using the polymer poly(N-isopropylacrylamide) (PNIPAAm) which can change its wettability when subjected to change in temperature. PNIPAAm is hydrophilic when the surface temperature is less than the lower critical solution temperature (LCST) range of about 28–33 °C and is hydrophobic above the LCST range. The PNIPAAm surface is heated by spiral gold microheaters which are fabricated on the lower side of the glass substrate. The contact angle change with change in temperature is tested using a standard goniometer. Time response analysis of the surface is presented. This smart surface can be used as an active or adaptive component for microflow regulation and can be potentially integrated into large scale lab-on-chip (LOC) systems.Copyright © 2008 by ASME

Fabrication and Characterization of Surface-Micromachined Compact Microheater for Gas Sensing Applications

Abstract: A surface-micromachined compact microheater for gas sensing applications fabricated on a silicon substrate is presented. The heater was fabricated with a compatible CMOS process and its membrane was released using XeF2 isotropic silicon etching. The membrane had SiO2/SixNy/SiO2 layers (0.4/0.3/0.3 mum) in order to restrict the initial stress after the release, resulting in less than 2.5 mum height deviation from the membrane center to the anchor. The circular-type Pt (0.18 mum) heater proposed in this paper has a diameter of 110 mum and a width of 5 mum. It also shows a 4-probe measured heater resistance of 10.9 Omega, while that of the theoretical heater is 8.5 Omega. Also, to evaluate its thermal performance, the MEMS heater was characterized using an empirical parameter extraction method. As the total thermal loss coefficient of the heater (G,A) was modeled to 1.68e-5 W/K at ambient temperature (Tamb, 293 K) and the temperature coefficient of resistance at room temperature (TCRamb) was determined to be 0.00312 1/K, the heater temperature, as a total dissipated power function, was extracted to 700 K at 31 mW.

Design and characterization of a microheater array device fabricated with SwIFT-Lite™

Abstract: A microheater array device is designed and fabricated using the SwIFT-LiteTM process at Sandia National Laboratories. The device contains 18 individually controllable microheaters in a 3×6 array on a silicon substrate. The microheater array device was designed for use as a biosensor platform with a waveguide for real-time detection of DNA hybridization and melting as well as microfluidics for sample delivery. The design process including modeling, fabrication, and characterization of the heaters and waveguide is detailed. A FRET (florescence resonance energy transfer) system for DNA melting experiments is described, and the associated surface chemistry and microfluidic systems are discussed.