Pub Date : 1989-02-20DOI: 10.1109/MEMSYS.1989.77957
L. Fan, R. Howe, R. Muller
A simple one-mask technique for characterizing fracture design parameters has been applied to tensile-stressed low-pressure chemical vapor deposited silicon nitride films. The design parameter obtained is the critical geometry parameter, which can be converted into fracture toughness by multiplying by the residual stress. Values of this parameter range from 14 to 290 mu m/sup 1/2/. Corresponding K/sub I/ values are from 4.2 MPa-m/sup 1/2/ to 87 MPa-m/sup 1/2/, assuming a residual stress of 300 MPa. Fabrication and test results are presented.<>
{"title":"Microstructures for fracture toughness characterization of brittle thin films","authors":"L. Fan, R. Howe, R. Muller","doi":"10.1109/MEMSYS.1989.77957","DOIUrl":"https://doi.org/10.1109/MEMSYS.1989.77957","url":null,"abstract":"A simple one-mask technique for characterizing fracture design parameters has been applied to tensile-stressed low-pressure chemical vapor deposited silicon nitride films. The design parameter obtained is the critical geometry parameter, which can be converted into fracture toughness by multiplying by the residual stress. Values of this parameter range from 14 to 290 mu m/sup 1/2/. Corresponding K/sub I/ values are from 4.2 MPa-m/sup 1/2/ to 87 MPa-m/sup 1/2/, assuming a residual stress of 300 MPa. Fabrication and test results are presented.<<ETX>>","PeriodicalId":369505,"journal":{"name":"IEEE Micro Electro Mechanical Systems, , Proceedings, 'An Investigation of Micro Structures, Sensors, Actuators, Machines and Robots'","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125587735","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 : 1989-02-20DOI: 10.1109/MEMSYS.1989.77975
L. Clayton, E. P. Eernisse, R. W. Ward, R.B. Wiggins
The photolithographic and chemical milling techniques used in fabricating a variety of three-dimensional monocrystalline quartz microstructures are presented. The piezoelectric effect, which is the electromechanical phenomenon utilized in the various applications of quartz technology, is described. Examples of quartz resonators used in sensing applications are presented. These miniature quartz sensors are incorporated into transducer systems which measure pressure, temperature, force, and acceleration. Some of the analytical tools used to design miniature quartz devices are outlined.<>
{"title":"Miniature crystalline quartz electronical structure","authors":"L. Clayton, E. P. Eernisse, R. W. Ward, R.B. Wiggins","doi":"10.1109/MEMSYS.1989.77975","DOIUrl":"https://doi.org/10.1109/MEMSYS.1989.77975","url":null,"abstract":"The photolithographic and chemical milling techniques used in fabricating a variety of three-dimensional monocrystalline quartz microstructures are presented. The piezoelectric effect, which is the electromechanical phenomenon utilized in the various applications of quartz technology, is described. Examples of quartz resonators used in sensing applications are presented. These miniature quartz sensors are incorporated into transducer systems which measure pressure, temperature, force, and acceleration. Some of the analytical tools used to design miniature quartz devices are outlined.<<ETX>>","PeriodicalId":369505,"journal":{"name":"IEEE Micro Electro Mechanical Systems, , Proceedings, 'An Investigation of Micro Structures, Sensors, Actuators, Machines and Robots'","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126675159","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 : 1989-02-20DOI: 10.1109/MEMSYS.1989.77976
M. Elwenspoek, F. Blom, S. Bouwstra, T. Lammerink, F.C.M. van de Pol, H. Tilmans, T. Popma, J. Fluitman
Transduction mechanisms and their applications in micromechanical actuators and resonating sensors are presented. They include piezoelectric, dielectric, electro-thermo-mechanic, opto-thermo-mechanic, and thermo-pneumatic mechanisms. Advantages and disadvantages with respect to technology and performance are discussed.<>
{"title":"Transduction mechanisms and their applications in micromechanical devices","authors":"M. Elwenspoek, F. Blom, S. Bouwstra, T. Lammerink, F.C.M. van de Pol, H. Tilmans, T. Popma, J. Fluitman","doi":"10.1109/MEMSYS.1989.77976","DOIUrl":"https://doi.org/10.1109/MEMSYS.1989.77976","url":null,"abstract":"Transduction mechanisms and their applications in micromechanical actuators and resonating sensors are presented. They include piezoelectric, dielectric, electro-thermo-mechanic, opto-thermo-mechanic, and thermo-pneumatic mechanisms. Advantages and disadvantages with respect to technology and performance are discussed.<<ETX>>","PeriodicalId":369505,"journal":{"name":"IEEE Micro Electro Mechanical Systems, , Proceedings, 'An Investigation of Micro Structures, Sensors, Actuators, Machines and Robots'","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115872745","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 : 1989-02-20DOI: 10.1109/MEMSYS.1989.77969
K. Najafi, K. Suzuki
A novel technique and test structure to measure the intrinsic stress and Young's modulus on thin films with better than 10% accuracy has been developed. The structure is a doubly supported beam that is driven electrostatically by a capacitive drive electrode in the middle of the beam. The characteristic pull-in voltage of the beam is used to measure the intrinsic stress and Young's modulus of thin films. An intrinsic stress of 1.83*10/sup 7/ Pa and a Young's modulus of 2.2*10/sup 11/ Pa for heavily boron-doped silicon structures have been measured. The technique can be easily applied to a number of other thin films including polysilicon and silicon nitride. The test structure occupies a small area.<>
{"title":"A novel technique and structure for the measurement of intrinsic stress and Young's modulus of thin films","authors":"K. Najafi, K. Suzuki","doi":"10.1109/MEMSYS.1989.77969","DOIUrl":"https://doi.org/10.1109/MEMSYS.1989.77969","url":null,"abstract":"A novel technique and test structure to measure the intrinsic stress and Young's modulus on thin films with better than 10% accuracy has been developed. The structure is a doubly supported beam that is driven electrostatically by a capacitive drive electrode in the middle of the beam. The characteristic pull-in voltage of the beam is used to measure the intrinsic stress and Young's modulus of thin films. An intrinsic stress of 1.83*10/sup 7/ Pa and a Young's modulus of 2.2*10/sup 11/ Pa for heavily boron-doped silicon structures have been measured. The technique can be easily applied to a number of other thin films including polysilicon and silicon nitride. The test structure occupies a small area.<<ETX>>","PeriodicalId":369505,"journal":{"name":"IEEE Micro Electro Mechanical Systems, , Proceedings, 'An Investigation of Micro Structures, Sensors, Actuators, Machines and Robots'","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115965163","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 : 1989-02-20DOI: 10.1109/MEMSYS.1989.77973
H. Allen, S. Terry, D. de Bruin
A novel approach to producing a high-reliability silicon accelerometer is described. The approach relies on the electrostatic deflection of the micromachined silicon mass. A number of key advantages result from this configuration. Even though the spring constants of the device may vary from unit to unit or over temperature, and even though the piezoresistive coefficients vary over temperature, as long as the electrostatic voltage and initial separation gap are held constant, the output is proportional to a given acceleration. Applications of this technology are in temperature compensation, testability and unidirectional force-balance applications.<>
{"title":"Self-testable accelerometer systems","authors":"H. Allen, S. Terry, D. de Bruin","doi":"10.1109/MEMSYS.1989.77973","DOIUrl":"https://doi.org/10.1109/MEMSYS.1989.77973","url":null,"abstract":"A novel approach to producing a high-reliability silicon accelerometer is described. The approach relies on the electrostatic deflection of the micromachined silicon mass. A number of key advantages result from this configuration. Even though the spring constants of the device may vary from unit to unit or over temperature, and even though the piezoresistive coefficients vary over temperature, as long as the electrostatic voltage and initial separation gap are held constant, the output is proportional to a given acceleration. Applications of this technology are in temperature compensation, testability and unidirectional force-balance applications.<<ETX>>","PeriodicalId":369505,"journal":{"name":"IEEE Micro Electro Mechanical Systems, , Proceedings, 'An Investigation of Micro Structures, Sensors, Actuators, Machines and Robots'","volume":"344 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134426329","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 : 1989-02-20DOI: 10.1109/MEMSYS.1989.77972
Y. Kim, M. Katsurai, H. Fujita
A superconducting actuator with magnetic levitation using Meissner effect in mu m order is proposed to remove the friction between moving elements and fixed elements in micromachines. The actuator, called Meissnac, is analyzed by the discrete surface current method. A driving method for the actuator is proposed. The driving force can be obtained by using the difference of the pitch of the stator and that of the slider, and the control of superconducting and normal states of superconductors. The control of the state can be achieved either by applying current over J/sub c/ to the superconductor or by heating it above T/sub c/. Maximum values of the levitating force and the driving force are 1.7 and 0.26 (N/m/sup 2/A/sup 2/). The lateral movement in a particular direction of a slider is obtained by choosing appropriate superconductors and by transforming them into the normal state. A scale model is fabricated using a YBaCuO high-T/sub c/ superconductor. The levitating force and the driving force of a scale model are 84 and 31 (mgf) when the slider is composed of a permanent magnet.<>
{"title":"A proposal for a superconducting actuator using Meissner effect","authors":"Y. Kim, M. Katsurai, H. Fujita","doi":"10.1109/MEMSYS.1989.77972","DOIUrl":"https://doi.org/10.1109/MEMSYS.1989.77972","url":null,"abstract":"A superconducting actuator with magnetic levitation using Meissner effect in mu m order is proposed to remove the friction between moving elements and fixed elements in micromachines. The actuator, called Meissnac, is analyzed by the discrete surface current method. A driving method for the actuator is proposed. The driving force can be obtained by using the difference of the pitch of the stator and that of the slider, and the control of superconducting and normal states of superconductors. The control of the state can be achieved either by applying current over J/sub c/ to the superconductor or by heating it above T/sub c/. Maximum values of the levitating force and the driving force are 1.7 and 0.26 (N/m/sup 2/A/sup 2/). The lateral movement in a particular direction of a slider is obtained by choosing appropriate superconductors and by transforming them into the normal state. A scale model is fabricated using a YBaCuO high-T/sub c/ superconductor. The levitating force and the driving force of a scale model are 84 and 31 (mgf) when the slider is composed of a permanent magnet.<<ETX>>","PeriodicalId":369505,"journal":{"name":"IEEE Micro Electro Mechanical Systems, , Proceedings, 'An Investigation of Micro Structures, Sensors, Actuators, Machines and Robots'","volume":"142 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122624395","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 : 1989-02-20DOI: 10.1109/MEMSYS.1989.77967
G. Koppelman
OYSTER simulated the geometric effects of sequential IC (integrated circuit) process stages, including patterning of photoresists with planar masks, in order to produce three-dimensional polyhedral representations of all material structures in a design cell after each process stage. It has been developed for IC simulation but is applicable to microelectromechanical systems manufactured using similar processes. The polyhedral models may be used with various analytic procedures as sources of geometric data for finite-element calculations, or they may be subjected to interference calculations, or inspected to detect structural anomalies. As used in IC simulations, OYSTER provides the ability to introduce worst-case or stochastic manufacturing variations in mask alignment, etch depth, or deposition thickness. The author presents examples of variations in mask alignment and calculates resultant variations in center of gravity and moments of inertia for simple micromechanical objects.<>
{"title":"OYSTER, a 3D structural simulator for microelectromechanical design","authors":"G. Koppelman","doi":"10.1109/MEMSYS.1989.77967","DOIUrl":"https://doi.org/10.1109/MEMSYS.1989.77967","url":null,"abstract":"OYSTER simulated the geometric effects of sequential IC (integrated circuit) process stages, including patterning of photoresists with planar masks, in order to produce three-dimensional polyhedral representations of all material structures in a design cell after each process stage. It has been developed for IC simulation but is applicable to microelectromechanical systems manufactured using similar processes. The polyhedral models may be used with various analytic procedures as sources of geometric data for finite-element calculations, or they may be subjected to interference calculations, or inspected to detect structural anomalies. As used in IC simulations, OYSTER provides the ability to introduce worst-case or stochastic manufacturing variations in mask alignment, etch depth, or deposition thickness. The author presents examples of variations in mask alignment and calculates resultant variations in center of gravity and moments of inertia for simple micromechanical objects.<<ETX>>","PeriodicalId":369505,"journal":{"name":"IEEE Micro Electro Mechanical Systems, , Proceedings, 'An Investigation of Micro Structures, Sensors, Actuators, Machines and Robots'","volume":"247 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132298755","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 : 1989-02-20DOI: 10.1109/MEMSYS.1989.77955
Masaki Esashi, Shuichi Shoji, Akira Nakano
A normally closed microvalve and micropump were fabricated on a silicon wafer by micromachining techniques. Normally closed microvalve has a silicon diaphragm and a small piezoelectric actuator to drive it. The controllable gas flow rate is from 0.1 ml/min to 85 ml/min at a gas pressure of 0.75 kgf/cm/sup 2/. The micropump is a diaphragm-type pump which consists of two polysilicon one-way valves and a diaphragm driven by a small piezoelectric actuator. The maximum pumping flow rate and pressure are 20 mu l/min and 780 mmH/sub 2/O/cm/sup 2/, respectively.<>
{"title":"Normally close microvalve and micropump fabricated on a silicon wafer","authors":"Masaki Esashi, Shuichi Shoji, Akira Nakano","doi":"10.1109/MEMSYS.1989.77955","DOIUrl":"https://doi.org/10.1109/MEMSYS.1989.77955","url":null,"abstract":"A normally closed microvalve and micropump were fabricated on a silicon wafer by micromachining techniques. Normally closed microvalve has a silicon diaphragm and a small piezoelectric actuator to drive it. The controllable gas flow rate is from 0.1 ml/min to 85 ml/min at a gas pressure of 0.75 kgf/cm/sup 2/. The micropump is a diaphragm-type pump which consists of two polysilicon one-way valves and a diaphragm driven by a small piezoelectric actuator. The maximum pumping flow rate and pressure are 20 mu l/min and 780 mmH/sub 2/O/cm/sup 2/, respectively.<<ETX>>","PeriodicalId":369505,"journal":{"name":"IEEE Micro Electro Mechanical Systems, , Proceedings, 'An Investigation of Micro Structures, Sensors, Actuators, Machines and Robots'","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129402778","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 : 1989-02-20DOI: 10.1109/MEMSYS.1989.77964
H. Guckel, J. Sniegowski, T. Christenson
The use of fine-grained polysilicon in the development of micromechanical devices (e.g. bearings, with smooth surfaces) is discussed. Fine-grained polysilicon can be produced with surface roughness near 8 AA r.m.s. (root mean square). The ability to anneal films of this type into tension eliminates size restrictions which are caused by compressive buckling. The use of these films in micromechanical devices has been restricted because hydrogen-fluoride-etched structures are covered by an etch residue which leads to contact welding. Contact between opposing surfaces is induced mainly by surface tension effects. This problem can be avoided by removing the deflection mechanism. Thus, freezing of a water-methanol rinse after sacrificial etching all but eliminates surface tension. Removal of the ice mixture via sublimation at 0.15 mbar occurs readily. Free-standing structures with smooth surfaces and small gaps are then passivated by silicon nitride deposition or other techniques.<>
细粒多晶硅在微机械设备(如轴承，表面光滑)的发展中的应用进行了讨论。细粒多晶硅可以生产表面粗糙度接近8 AA r.m.s.(均方根)。将这种类型的薄膜退火成张力的能力消除了由压缩屈曲引起的尺寸限制。这些薄膜在微机械装置中的使用受到限制，因为氟化氢蚀刻结构被蚀刻残留物覆盖，导致接触焊接。相对表面之间的接触主要是由表面张力效应引起的。这个问题可以通过移除偏转机构来避免。因此，在牺牲蚀刻后冷冻水-甲醇冲洗几乎消除了表面张力。在0.15毫巴的温度下通过升华很容易除去冰混合物。具有光滑表面和小间隙的独立结构然后通过氮化硅沉积或其他技术钝化。
{"title":"Advances in processing techniques for silicon micromechanical devices with smooth surfaces","authors":"H. Guckel, J. Sniegowski, T. Christenson","doi":"10.1109/MEMSYS.1989.77964","DOIUrl":"https://doi.org/10.1109/MEMSYS.1989.77964","url":null,"abstract":"The use of fine-grained polysilicon in the development of micromechanical devices (e.g. bearings, with smooth surfaces) is discussed. Fine-grained polysilicon can be produced with surface roughness near 8 AA r.m.s. (root mean square). The ability to anneal films of this type into tension eliminates size restrictions which are caused by compressive buckling. The use of these films in micromechanical devices has been restricted because hydrogen-fluoride-etched structures are covered by an etch residue which leads to contact welding. Contact between opposing surfaces is induced mainly by surface tension effects. This problem can be avoided by removing the deflection mechanism. Thus, freezing of a water-methanol rinse after sacrificial etching all but eliminates surface tension. Removal of the ice mixture via sublimation at 0.15 mbar occurs readily. Free-standing structures with smooth surfaces and small gaps are then passivated by silicon nitride deposition or other techniques.<<ETX>>","PeriodicalId":369505,"journal":{"name":"IEEE Micro Electro Mechanical Systems, , Proceedings, 'An Investigation of Micro Structures, Sensors, Actuators, Machines and Robots'","volume":"14 38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128628153","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 : 1989-02-20DOI: 10.1109/MEMSYS.1989.77978
K. Kuribayashi
A millimeter-size actuator to drive a rotary joint for a small robot was designed and fabricated using shape memory alloy (SMA), which has the merits of large force/weight and extendability to micron size. The actuator is of the push-pull type, composed of two SMA sheets of 0.05 mm*0.5 mm*3 mm. The theoretical model of the dynamics of the SMA actuator was derived based on an experimental analysis of the dynamics of the larger SMA sheets. Using this model, the design method of the SMA actuator was established. Finally, the theoretical torque vs. angular displacement characteristic of a millimeter-size rotary joint driven by the above millimeter-size SMA actuator was obtained, which shows a maximum of 4 gf-mm.<>
{"title":"Millimeter size joint actuator using shape memory alloy","authors":"K. Kuribayashi","doi":"10.1109/MEMSYS.1989.77978","DOIUrl":"https://doi.org/10.1109/MEMSYS.1989.77978","url":null,"abstract":"A millimeter-size actuator to drive a rotary joint for a small robot was designed and fabricated using shape memory alloy (SMA), which has the merits of large force/weight and extendability to micron size. The actuator is of the push-pull type, composed of two SMA sheets of 0.05 mm*0.5 mm*3 mm. The theoretical model of the dynamics of the SMA actuator was derived based on an experimental analysis of the dynamics of the larger SMA sheets. Using this model, the design method of the SMA actuator was established. Finally, the theoretical torque vs. angular displacement characteristic of a millimeter-size rotary joint driven by the above millimeter-size SMA actuator was obtained, which shows a maximum of 4 gf-mm.<<ETX>>","PeriodicalId":369505,"journal":{"name":"IEEE Micro Electro Mechanical Systems, , Proceedings, 'An Investigation of Micro Structures, Sensors, Actuators, Machines and Robots'","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122949413","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}
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