USU ECE 5320 - Thermal Bimorph Actuators

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ECE5320 Mechatronics Assignment#1: Literature Survey on Sensors and Actuators Topic: Thermal Bimorph ActuatorsOutlineThermal Bimorph ActuatorsBasic StructureBasic working principle illustratedSlide 6Major ApplicationsThermal Bimorph MicromirrorSlide 9Slide 10Dip Pen Nanolithography (DPN)DPN – AFM ProbesSlide 13DPNAFM ProbesControl of Thermal BimorphsSlide 17Model of Thermal BimorphsTo Probe FurtherReference listDoug DainesECE5320 MechatronicsAssignment#1: Assignment#1: Literature Survey on Sensors and Actuators Literature Survey on Sensors and Actuators Topic: Thermal Bimorph ActuatorsPrepared by:Douglas Daines3/10/200601/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-2Doug DainesOutline –Definition–Basic structure–Major applications–Basic working principle illustrated–Major applications–Design applications–Control–Model–Reference list–To probe further01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-3Doug DainesThermal Bimorph Actuators•Thermal bimorph actuators operate on the principle of thermal expansion. Two substrates are combined that have different expansion rates. When heated it results in bending of the material.•“Electro-thermal actuations are very attractive since they can generate large deflections and forces with low actuating voltages and their fabrication process is compatible with the general integrated circuit (IC) fabrication process.”An electro-thermal bimorph-based microactuator for precise track-positioning of optical disk drives J P Yang, X C Deng and T C Chong01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-4Doug DainesBasic Structure•Thermal Bimorphs are generally etched into silicon•They are designed on the order of 10’s to100’s of micrometers•To facilitate even bending of a surface, the surfaces arms are kept very narrow–For a wide surface, the surface is etched into a comb structureMEMS actuators Professor Mark Bachman01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-5Doug DainesBasic working principle illustrated•Voltage is applied to the actuator•The two parts of the actuator expand as they are heated•One side expands faster than the other resulting in curvature01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-6Doug DainesBasic working principle illustrated•Many different types of material can be used–Metals–Semiconductors–Ceramics–Polymers01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-7Doug DainesMajor Applications•Optical displays•Biomedical imaging •Laser beam steering •Optical switching•Fast-scanning mirrors that can generate piston motion are required by applications for wave-front shaping in adaptive optics •Interferometry systems•Spatial light modulators•Tunable lenses for confocal microscopy •Microvalves •Actuators on magnetic recording heads•Precision micro positioning systemsA thermal bimorph micromirror with large bi-directional and vertical actuation Ankur Jain, Hongwei Qu, Shane Todd, Huikai Xie01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-8Doug DainesThermal Bimorph Micromirror•The bimorph actuation structure is composed of aluminum and silicon dioxide with an embedded polysilicon thermal resistor. •With a size of only 0.7mm×0.32 mm, the micromirror demonstrated a vertical displacement of 0.2mm at 6V dc. A thermal bimorph micromirror with large bi-directional and vertical actuation Ankur Jain, Hongwei Qu, Shane Todd, Huikai Xie01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-9Doug DainesThermal Bimorph Micromirror“This device can be used to perform bi-directional rotational scanning through the use of two bimorph actuators. The micromirror rotates over ±15◦ at less than 6V dc, and over ±43◦ (i.e., >170◦ optical scan angle) at its resonant frequency of 2.6 kHz.”01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-10Doug DainesThermal Bimorph Micromirror•Limitations–Small displacements•~200µm for a device 700µm×320µm in size.–Designed for precision systems–Very sensitive to external temperature•Benefits–The fabrication process is simple and compatible with CMOS processes. Because of this, control circuitry can be integrated with the mirror on the same chip.01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-11Doug DainesDip Pen Nanolithography (DPN)•“In Dip Pen Nanolithography (DPN), arbitrary nanoscale chemical patterns can be created by the diffusion of chemicals from the tip of an atomic force microscope (AFM) probe to a surface.”•The probe array is 10 thermal bimorph probes made of silicon nitride and gold. The probes are 300 µm long and the tips are spaced at 100 µm intervals.Design, Fabrication, and Characterization of Thermally Actuated Probe Arrays for Dip Pen Nanolithography David Bullen, Xuefeng Wang, Jun Zou, Member, IEEE, Sung-Wook Chung, Chad A. Mirkin, and Chang Liu01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-12Doug DainesDPN – AFM Probes•Each probe is a thermal actuator, enabling it to lift itself from the surface•The actuator moves the probe tip up 8µm with a current of 10mA10 probe DPN array. The inset shows a close-up of the tip01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-13Doug DainesDPN – AFM Probes“Each probe is made of silicon nitride with a molded pyramid tip at its free end. The addition of a gold layer on the tip side of the cantilever creates a bimorph actuator.“Thermal bimorph actuation was chosen in lieu of other actuation methods because of its small footprint, large deflection, low voltage operation, and ease of fabrication.“The heat supplied by the resistive heater is treated as a function of temperature due the relatively large temperature coefficient of resistance of the heater material.”01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-14Doug DainesDPN•The array is demonstrated by using it to simultaneously write 10 unique octadecanethiol patterns on a gold surface.Individual pictures are 8µm x 8µm01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-15Doug DainesAFM Probes•Limitations–Contact forces can easily damage


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USU ECE 5320 - Thermal Bimorph Actuators

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