Pub Date : 2002-12-16DOI: 10.1109/JMEMS.2002.805208
Jinling Yang, T. Ono, M. Esashi
Discusses four kinds of mechanical energy losses in ultrathin micro-cantilevers of 60 nm, 170 nm, and 500 nm in thickness: thermoelastic loss, air damping, support loss, and surface loss. For the cantilevers with thickness H 10 /spl mu/m, thermoelastic loss is negligible. But it becomes significant when the beam thickness H>500 nm and the length L 30 /spl mu/m, the Q factors of the cantilevers are proportional to their thickness, i.e., surface loss dominates the mechanical behavior. Annealing the cantilevers of 170 nm thickness at 1000/spl deg/C for 30 s under an ultrahigh vacuum (UHV) condition results in an over one order-of-magnitude increase of the Q factor, up to about 2.5/spl times/10/sup 5/ for cantilevers of 30-90 /spl mu/m in length.
{"title":"Energy dissipation in submicrometer thick single-crystal silicon cantilevers","authors":"Jinling Yang, T. Ono, M. Esashi","doi":"10.1109/JMEMS.2002.805208","DOIUrl":"https://doi.org/10.1109/JMEMS.2002.805208","url":null,"abstract":"Discusses four kinds of mechanical energy losses in ultrathin micro-cantilevers of 60 nm, 170 nm, and 500 nm in thickness: thermoelastic loss, air damping, support loss, and surface loss. For the cantilevers with thickness H 10 /spl mu/m, thermoelastic loss is negligible. But it becomes significant when the beam thickness H>500 nm and the length L 30 /spl mu/m, the Q factors of the cantilevers are proportional to their thickness, i.e., surface loss dominates the mechanical behavior. Annealing the cantilevers of 170 nm thickness at 1000/spl deg/C for 30 s under an ultrahigh vacuum (UHV) condition results in an over one order-of-magnitude increase of the Q factor, up to about 2.5/spl times/10/sup 5/ for cantilevers of 30-90 /spl mu/m in length.","PeriodicalId":13438,"journal":{"name":"IEEE\\/ASME Journal of Microelectromechanical Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79121687","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-12-16DOI: 10.1109/JMEMS.2002.805210
M. Baker, M. P. Boer, N. F. Smith, L. Warne, M. Sinclair
Two methodologies have been developed to determine the biaxial residual stress value in thin films using electrostatically actuated fixed-fixed beam test structures. In the first, we determine the compliance matrix of the support posts using 3-D finite-element analysis. The residual stress value is then found from the best fit between the measured and modeled deflection curves, with the residual stress as the only free parameter in the model. An accuracy of /spl plusmn/0.5 MPa for the average biaxial residual stress level is evaluated from the reproducibility of independent measurements over a wide range of loadings. The key to the second methodology lies in the recognition that for a given value of residual stress, there exists a unique family of deflection curves associated with two adjacent beams of different lengths. Therefore, compliance information can be extracted directly from the deflection curves. We proceed to show that essentially the same values of residual stress are found by the two methodologies, while the latter allows much more rapid extraction of the residual stress. With the second methodology established, we find that residual stress values vary across a quarter of a six-inch diameter wafer by 2.5 MPa for three structural levels of polycrystalline silicon in our five-level surface micromachining technology.
{"title":"Integrated measurement-modeling approaches for evaluating residual stress using micromachined fixed-fixed beams","authors":"M. Baker, M. P. Boer, N. F. Smith, L. Warne, M. Sinclair","doi":"10.1109/JMEMS.2002.805210","DOIUrl":"https://doi.org/10.1109/JMEMS.2002.805210","url":null,"abstract":"Two methodologies have been developed to determine the biaxial residual stress value in thin films using electrostatically actuated fixed-fixed beam test structures. In the first, we determine the compliance matrix of the support posts using 3-D finite-element analysis. The residual stress value is then found from the best fit between the measured and modeled deflection curves, with the residual stress as the only free parameter in the model. An accuracy of /spl plusmn/0.5 MPa for the average biaxial residual stress level is evaluated from the reproducibility of independent measurements over a wide range of loadings. The key to the second methodology lies in the recognition that for a given value of residual stress, there exists a unique family of deflection curves associated with two adjacent beams of different lengths. Therefore, compliance information can be extracted directly from the deflection curves. We proceed to show that essentially the same values of residual stress are found by the two methodologies, while the latter allows much more rapid extraction of the residual stress. With the second methodology established, we find that residual stress values vary across a quarter of a six-inch diameter wafer by 2.5 MPa for three structural levels of polycrystalline silicon in our five-level surface micromachining technology.","PeriodicalId":13438,"journal":{"name":"IEEE\\/ASME Journal of Microelectromechanical Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73632512","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-12-16DOI: 10.1109/JMEMS.2002.805214
C. Tsau, S. Spearing, M. Schmidt
Thermocompression bonding of gold is a promising technique for achieving low temperature, wafer-level bonding. The fabrication process for wafer bonding at 300/spl deg/C via compressing gold under 7 MPa of pressure is described in detail. One of the issues encountered in the process development was e-beam source spitting, which resulted in micrometer diameter sized Au on the surfaces, and made bonding difficult. The problem was solved by inserting a tungsten liner to the graphite crucible. Surface segregation of Si on the Au surface at the bonding temperature was observed. Using Auger spectroscopy, a 1500 /spl Aring/ SiO/sub 2/ barrier layer was shown to be sufficient in preventing Si from reaching the surface. Lastly, a four-point bend delamination technique was used to quantify the bond toughness. The associated process steps that were required to prepare the test specimens are described. The critical strain energy release rate for the bonds ranged between 22 to 67 J/m/sup 2/ and was not shown to be strongly associated with the gold bond layer thickness in the thickness range studied (0.23 to 1.4 /spl mu/m).
{"title":"Fabrication of wafer-level thermocompression bonds","authors":"C. Tsau, S. Spearing, M. Schmidt","doi":"10.1109/JMEMS.2002.805214","DOIUrl":"https://doi.org/10.1109/JMEMS.2002.805214","url":null,"abstract":"Thermocompression bonding of gold is a promising technique for achieving low temperature, wafer-level bonding. The fabrication process for wafer bonding at 300/spl deg/C via compressing gold under 7 MPa of pressure is described in detail. One of the issues encountered in the process development was e-beam source spitting, which resulted in micrometer diameter sized Au on the surfaces, and made bonding difficult. The problem was solved by inserting a tungsten liner to the graphite crucible. Surface segregation of Si on the Au surface at the bonding temperature was observed. Using Auger spectroscopy, a 1500 /spl Aring/ SiO/sub 2/ barrier layer was shown to be sufficient in preventing Si from reaching the surface. Lastly, a four-point bend delamination technique was used to quantify the bond toughness. The associated process steps that were required to prepare the test specimens are described. The critical strain energy release rate for the bonds ranged between 22 to 67 J/m/sup 2/ and was not shown to be strongly associated with the gold bond layer thickness in the thickness range studied (0.23 to 1.4 /spl mu/m).","PeriodicalId":13438,"journal":{"name":"IEEE\\/ASME Journal of Microelectromechanical Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78910495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-12-16DOI: 10.1109/JMEMS.2002.805206
E. Chow, V. Chandrasekaran, A. Partridge, T. Nishida, M. Sheplak, C. Quate, T. Kenny
Electrical through-wafer interconnects (ETWI) which connect devices between both sides of a substrate are critical components for microelectromechanical systems (MEMS) and integrated circuits (IC), as they enable three-dimensional (3-D) structures and permit new packaging and integration geometries. Previously demonstrated ETWI are very difficult to integrate with standard semiconductor fabrication processes, not compatible with released sensors, do not permit extensive processing on both sides of the wafer, and are in general very application specific. This work describes the design, fabrication, and characterization of an ETWI technology for silicon substrates that can be broadly integrated with MEMS and IC processes. This interconnect is a passively isolated electrical through-wafer polysilicon plug, with a 20 /spl mu/m diameter, 10-14 /spl Omega/ resistance, and less than 1 pF capacitance. Plasma etching from both sides of the wafer is used to achieve a high-aspect ratio via (20:1 through 400 /spl mu/m). The process is compatible with standard lithography, standard wafer handling, subsequent high-temperature processing, and released sensors integration. N-type and p-type versions are demonstrated, and isolated ground planes are added to provide shielding against substrate noise. Electrical properties of these ETWI are measured and analytically modeled. These ETWI are appropriate for integration with devices with impedances much greater than the ETWI, such as piezoresistive and capacitive sensor arrays.
{"title":"Process compatible polysilicon-based electrical through-wafer interconnects in silicon substrates","authors":"E. Chow, V. Chandrasekaran, A. Partridge, T. Nishida, M. Sheplak, C. Quate, T. Kenny","doi":"10.1109/JMEMS.2002.805206","DOIUrl":"https://doi.org/10.1109/JMEMS.2002.805206","url":null,"abstract":"Electrical through-wafer interconnects (ETWI) which connect devices between both sides of a substrate are critical components for microelectromechanical systems (MEMS) and integrated circuits (IC), as they enable three-dimensional (3-D) structures and permit new packaging and integration geometries. Previously demonstrated ETWI are very difficult to integrate with standard semiconductor fabrication processes, not compatible with released sensors, do not permit extensive processing on both sides of the wafer, and are in general very application specific. This work describes the design, fabrication, and characterization of an ETWI technology for silicon substrates that can be broadly integrated with MEMS and IC processes. This interconnect is a passively isolated electrical through-wafer polysilicon plug, with a 20 /spl mu/m diameter, 10-14 /spl Omega/ resistance, and less than 1 pF capacitance. Plasma etching from both sides of the wafer is used to achieve a high-aspect ratio via (20:1 through 400 /spl mu/m). The process is compatible with standard lithography, standard wafer handling, subsequent high-temperature processing, and released sensors integration. N-type and p-type versions are demonstrated, and isolated ground planes are added to provide shielding against substrate noise. Electrical properties of these ETWI are measured and analytically modeled. These ETWI are appropriate for integration with devices with impedances much greater than the ETWI, such as piezoresistive and capacitive sensor arrays.","PeriodicalId":13438,"journal":{"name":"IEEE\\/ASME Journal of Microelectromechanical Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77920547","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-12-16DOI: 10.1109/JMEMS.2002.805207
A. Seshia, Moorthi Palaniapan, T. Roessig, R. Howe, R. Gooch, T. Schimert, Stephen Montague
This paper describes the operation of a vacuum packaged resonant accelerometer subjected to static and dynamic acceleration testing. The device response is in broad agreement with a new analytical model of its behavior under an applied time-varying acceleration. Measurements include tests of the scale factor of the sensor and the dependence of the output sideband power and the noise floor of the double-ended tuning fork oscillators as a function of the applied acceleration frequency. The resolution of resonant accelerometers is shown to degrade 20 dB/decade beyond a certain characteristic acceleration corner frequency. A prototype device was fabricated at Sandia National Laboratories and exhibits a noise floor of 40 /spl mu/g//spl radic/(Hz) for an input acceleration frequency of 300 Hz.
{"title":"A vacuum packaged surface micromachined resonant accelerometer","authors":"A. Seshia, Moorthi Palaniapan, T. Roessig, R. Howe, R. Gooch, T. Schimert, Stephen Montague","doi":"10.1109/JMEMS.2002.805207","DOIUrl":"https://doi.org/10.1109/JMEMS.2002.805207","url":null,"abstract":"This paper describes the operation of a vacuum packaged resonant accelerometer subjected to static and dynamic acceleration testing. The device response is in broad agreement with a new analytical model of its behavior under an applied time-varying acceleration. Measurements include tests of the scale factor of the sensor and the dependence of the output sideband power and the noise floor of the double-ended tuning fork oscillators as a function of the applied acceleration frequency. The resolution of resonant accelerometers is shown to degrade 20 dB/decade beyond a certain characteristic acceleration corner frequency. A prototype device was fabricated at Sandia National Laboratories and exhibits a noise floor of 40 /spl mu/g//spl radic/(Hz) for an input acceleration frequency of 300 Hz.","PeriodicalId":13438,"journal":{"name":"IEEE\\/ASME Journal of Microelectromechanical Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77360905","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-12-16DOI: 10.1109/JMEMS.2002.802909
Jr-Hung Tsai, Liwei Lin
A thermal-bubble-actuated micropump by the principles of liquid/vapor phase transition and nozzle-diffuser flow regulation is successfully demonstrated. The micropump consists of a resistive heater, a pair of nozzle-diffuser flow controller and a 1 mm in diameter, 50 /spl mu/m in depth pumping chamber. The actuation mechanism comes from periodically nucleating and collapsing thermal bubbles. A net flow is generated from the nozzle to the diffuser by the nozzle-diffuser flow controller. Two heater designs, single-bubble and dual-bubble actuation mode, have been investigated. In the single-bubble pumping mode, a maximum flow rate of 5 /spl mu/l/min is measured when the driving pulse is 250 Hz at 10% duty cycle under an average power consumption of 1 W. A similar flow rate of 4.5 /spl mu/l/min is achieved in the dual-bubble pumping mode, at the driving pulse of 5% duty cycle at 400 Hz with lower average power consumption, 0.5 W. The static pumping pressure is measured at a maximum value of 377 Pascal when the net volume flow rate is zero. As an application example in a microfluidic device, this valve-less micropump is used in a microfluidic system to enhance the fluid mixing by agitating the flows.
{"title":"A thermal-bubble-actuated micronozzle-diffuser pump","authors":"Jr-Hung Tsai, Liwei Lin","doi":"10.1109/JMEMS.2002.802909","DOIUrl":"https://doi.org/10.1109/JMEMS.2002.802909","url":null,"abstract":"A thermal-bubble-actuated micropump by the principles of liquid/vapor phase transition and nozzle-diffuser flow regulation is successfully demonstrated. The micropump consists of a resistive heater, a pair of nozzle-diffuser flow controller and a 1 mm in diameter, 50 /spl mu/m in depth pumping chamber. The actuation mechanism comes from periodically nucleating and collapsing thermal bubbles. A net flow is generated from the nozzle to the diffuser by the nozzle-diffuser flow controller. Two heater designs, single-bubble and dual-bubble actuation mode, have been investigated. In the single-bubble pumping mode, a maximum flow rate of 5 /spl mu/l/min is measured when the driving pulse is 250 Hz at 10% duty cycle under an average power consumption of 1 W. A similar flow rate of 4.5 /spl mu/l/min is achieved in the dual-bubble pumping mode, at the driving pulse of 5% duty cycle at 400 Hz with lower average power consumption, 0.5 W. The static pumping pressure is measured at a maximum value of 377 Pascal when the net volume flow rate is zero. As an application example in a microfluidic device, this valve-less micropump is used in a microfluidic system to enhance the fluid mixing by agitating the flows.","PeriodicalId":13438,"journal":{"name":"IEEE\\/ASME Journal of Microelectromechanical Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74343948","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-12-16DOI: 10.1109/JMEMS.2002.805042
Jaehyoung Park, H. Kim, W. Choi, Y. Kwon, Yong-Kweon Kim
Micromachined reflection-type phase shifters with small size and low loss for V-band communication systems are described. Two- and three-bit reflection type phase shifters were designed, fabricated, and measured. The micromachined air-gap overlay coupler and the direct contact type series switches were employed to implement the phase shift and reduce an insertion loss. The phase shift can be obtained by changing the length of the open-ended stubs using the cascaded MEMS switches. The fabricated two-bit phase shifter has a measured phase shift of 0/spl deg/, 41.5/spl deg/, 84.3/spl deg/, and 128.7/spl deg/ with the consecutive actuation of the series MEMS switches. The actuation voltage of the switches is 35 V and the measured switching ON time is 5.1 /spl mu/s. The average insertion loss of the two-bit phase shifter measured 4.1 dB at 60 GHz and the return losses for all phase shift states are better than 11.7 dB from 50 to 70 GHz. The two-bit phase shifter is small, 1.5 mm /spl times/ 2.1 mm. By cascading the two-bit phase shifter and a 180/spl deg/ phase shifter (one-bit), a three-bit phase shifter is realized, which has a phase shift of 265.5/spl deg/ and an average insertion loss of 4.85 dB at 60 GHz. The size of the three-bit phase shifter is 3.2 mm /spl times/ 2.1 mm.
{"title":"V-band reflection-type phase shifters using micromachined CPW coupler and RF switches","authors":"Jaehyoung Park, H. Kim, W. Choi, Y. Kwon, Yong-Kweon Kim","doi":"10.1109/JMEMS.2002.805042","DOIUrl":"https://doi.org/10.1109/JMEMS.2002.805042","url":null,"abstract":"Micromachined reflection-type phase shifters with small size and low loss for V-band communication systems are described. Two- and three-bit reflection type phase shifters were designed, fabricated, and measured. The micromachined air-gap overlay coupler and the direct contact type series switches were employed to implement the phase shift and reduce an insertion loss. The phase shift can be obtained by changing the length of the open-ended stubs using the cascaded MEMS switches. The fabricated two-bit phase shifter has a measured phase shift of 0/spl deg/, 41.5/spl deg/, 84.3/spl deg/, and 128.7/spl deg/ with the consecutive actuation of the series MEMS switches. The actuation voltage of the switches is 35 V and the measured switching ON time is 5.1 /spl mu/s. The average insertion loss of the two-bit phase shifter measured 4.1 dB at 60 GHz and the return losses for all phase shift states are better than 11.7 dB from 50 to 70 GHz. The two-bit phase shifter is small, 1.5 mm /spl times/ 2.1 mm. By cascading the two-bit phase shifter and a 180/spl deg/ phase shifter (one-bit), a three-bit phase shifter is realized, which has a phase shift of 265.5/spl deg/ and an average insertion loss of 4.85 dB at 60 GHz. The size of the three-bit phase shifter is 3.2 mm /spl times/ 2.1 mm.","PeriodicalId":13438,"journal":{"name":"IEEE\\/ASME Journal of Microelectromechanical Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80787079","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-12-16DOI: 10.1109/JMEMS.2002.803283
W. King, T. Kenny, K. Goodson, G. Cross, M. Despont, U. Dürig, H. Rothuizen, G. Binnig, P. Vettiger
In thermomechanical data writing, a resistively-heated atomic force microscope (AFM) cantilever tip forms indentations in a thin polymer film. The same cantilever operates as a thermal proximity sensor to detect the presence of previously written data bits. This paper uses recent progress in thermal analysis of the writing and reading modes to develop new cantilever designs for increased speed, sensitivity, and reduced power consumption in both writing and reading operation. Measurements of cantilever electrical resistance during heating reveals physical limits of cantilever writing and reading, and verifies a finite-difference thermal and electrical simulation of cantilever operation. This work proposes two new cantilever designs that correspond to fabrication technology benchmarks. Simulations predict that the proposed cantilevers have a higher data rate and are more sensitive than the present cantilever. The various cantilever designs offer single-bit writing times of 0.2 /spl mu/s-25 /spl mu/s for driving voltages of 2-25 V. The thermal reading /spl Delta/R/R sensitivity is as high as 4/spl times/10/sup -4/ per vertical nm in near steady-state operation.
{"title":"Design of atomic force microscope cantilevers for combined thermomechanical writing and thermal reading in array operation","authors":"W. King, T. Kenny, K. Goodson, G. Cross, M. Despont, U. Dürig, H. Rothuizen, G. Binnig, P. Vettiger","doi":"10.1109/JMEMS.2002.803283","DOIUrl":"https://doi.org/10.1109/JMEMS.2002.803283","url":null,"abstract":"In thermomechanical data writing, a resistively-heated atomic force microscope (AFM) cantilever tip forms indentations in a thin polymer film. The same cantilever operates as a thermal proximity sensor to detect the presence of previously written data bits. This paper uses recent progress in thermal analysis of the writing and reading modes to develop new cantilever designs for increased speed, sensitivity, and reduced power consumption in both writing and reading operation. Measurements of cantilever electrical resistance during heating reveals physical limits of cantilever writing and reading, and verifies a finite-difference thermal and electrical simulation of cantilever operation. This work proposes two new cantilever designs that correspond to fabrication technology benchmarks. Simulations predict that the proposed cantilevers have a higher data rate and are more sensitive than the present cantilever. The various cantilever designs offer single-bit writing times of 0.2 /spl mu/s-25 /spl mu/s for driving voltages of 2-25 V. The thermal reading /spl Delta/R/R sensitivity is as high as 4/spl times/10/sup -4/ per vertical nm in near steady-state operation.","PeriodicalId":13438,"journal":{"name":"IEEE\\/ASME Journal of Microelectromechanical Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81872566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-12-16DOI: 10.1109/JMEMS.2002.805055
Chuan-Hua Chen, J. Santiago
Electroosmotic (EO) micropumps use field-induced ion drag to drive liquids and achieve high pressures in a compact design with no moving parts. An analytical model applicable to planar, etched-structure micropumps has been developed. This model consists of pressure and flow relations in addition to an analytical expression that can be used to estimate the thermodynamic efficiency of planar EO pumps. The analytical model was applied to guide the design of a pump consisting of an etched EO flow chamber for near-optimal hydraulic power performance. To achieve high efficiency, the working fluid used was deionized (DI) water with a conductivity of 3.0 /spl times/ 10/sup -4/ S/m (pH = 5.7). The EO micropump was fabricated on a soda-lime glass substrate using standard microlithography and chemical wet etching techniques. The active pumping volume of the device consists of a wet-etched flow channel 1-mm long in the flow direction and 0.9 /spl mu/m by 38-mm in cross section. The pump performance agrees well with the theoretical model. The pump can produce a maximum pressure of 0.33 atm and a maximum flow rate of 15 /spl mu/L/min min at 1 kV.
{"title":"A planar electroosmotic micropump","authors":"Chuan-Hua Chen, J. Santiago","doi":"10.1109/JMEMS.2002.805055","DOIUrl":"https://doi.org/10.1109/JMEMS.2002.805055","url":null,"abstract":"Electroosmotic (EO) micropumps use field-induced ion drag to drive liquids and achieve high pressures in a compact design with no moving parts. An analytical model applicable to planar, etched-structure micropumps has been developed. This model consists of pressure and flow relations in addition to an analytical expression that can be used to estimate the thermodynamic efficiency of planar EO pumps. The analytical model was applied to guide the design of a pump consisting of an etched EO flow chamber for near-optimal hydraulic power performance. To achieve high efficiency, the working fluid used was deionized (DI) water with a conductivity of 3.0 /spl times/ 10/sup -4/ S/m (pH = 5.7). The EO micropump was fabricated on a soda-lime glass substrate using standard microlithography and chemical wet etching techniques. The active pumping volume of the device consists of a wet-etched flow channel 1-mm long in the flow direction and 0.9 /spl mu/m by 38-mm in cross section. The pump performance agrees well with the theoretical model. The pump can produce a maximum pressure of 0.33 atm and a maximum flow rate of 15 /spl mu/L/min min at 1 kV.","PeriodicalId":13438,"journal":{"name":"IEEE\\/ASME Journal of Microelectromechanical Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86199312","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-12-16DOI: 10.1109/JMEMS.2002.803416
M. W. Losey, R. J. Jackman, S. Firebaugh, M. Schmidt, K. Jensen
Using silicon microfabrication technology, microchemical devices have been constructed for the purpose of conducting heterogeneously catalyzed multiphase reactions. The motivation behind the design, the fabrication approach, and the experimental characterization are presented for two classes of devices. The first design involves multiple parallel channels with integrated filter structures to incorporate standard catalytic materials. These catalysts are in the form of finely divided porous particles in a packed-bed arrangement. The second device involves the incorporation of porous silicon as a catalyst support, in the form of a thin layer covering microstructured channels. These microstructured channels simulate the structure of a packed bed and enhance mass transfer relative to an open channel. The ability to incorporate features at the tens-of-microns scale can reduce the mass-transfer limitations by promoting mixing and dispersion for the multiple phases. Directly integrating the catalyst support structures into the channels of the microreactor allows the precise definition of the bed properties, including the support's size, shape and arrangement, and the void fraction. Such a design would find broad applicability in enhancing the transport and active surface area for sensing, chemical, and biochemical conversion devices. Reaction rates for the gas-liquid-solid hydrogenation of cyclohexene using the integrated catalyst with porous silicon as a support compare favorably to those rates obtained with the packed-bed approach. In both cases, the mass transfer coefficient is at least 100 times better than conventional laboratory reactors.
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