Bimorph

About: Bimorph is a research topic. Over the lifetime, 3339 publications have been published within this topic receiving 51880 citations.

Flexure Mode Piezoelectric Transducers

Abstract: Although flexurally responsive piezoelectric elements have been utilized for a few decades, interest in their utility remains high. This is a result of the ability of such structures to generate high output from sources of low mechanical impedance, or, conversely, to develop large displacement at low levels of electrical excitation. Typically a bending response is obtained from a sandwichlike structure of two properly oriented piezoelectric expander plates in which case the unit is referred to as a bender Bimorph. However, other approaches to benders include the Unimorph, the Multimorph, and other specially treated single plate elements. Numerous applications utilizing bender elements exist. To aid in meeting the variety of requirements presented by these applications, the supplier has available to him many options. These variables include choice of materials, geometry, and electrode configurations. In terms of volume of usage, the phonograph cartridge remains the number one application. However, many other electroacoustical devices are made possible by the availability of the Bimorph or its modified alternates Some of these are indicated. In addition, the utility of the equivalent circuit and its constants are described.

Numerical modeling of shape and topology optimisation of a piezoelectric cantilever beam in an energy-harvesting sensor

Abstract: Piezoelectric materials are excellent transducers for converting mechanical energy from the environment for use as electrical energy. The conversion of mechanical energy to electrical energy is a key component in the development of self-powered devices, especially enabling technology for wireless sensor networks. This paper proposes an alternative method for predicting the power output of a bimorph cantilever beam using a finite-element method for both static and dynamic frequency analyses. A novel approach is presented for optimising the cantilever beam, by which the power density is maximised and the structural volume is minimised simultaneously. A two-stage optimisation is performed, i.e., a shape optimisation and then a "topology" hole opening optimisation.

Scanning device using fiber optic bimorph

Abstract: An optical scanner employs a cantilever-mounted optical fiber within a micro electro-mechanical systems (MEMS) motor. In an embodiment, the fiber is sandwiched between two piezoelectric elements to form a unitary bimorph. The bimorph is excited with opposite polarity to cause it to bend rapidly in a plane. The light collected from the tip is projected to a small spot on the scanned medium. The bimorph is oscillated by applying an alternating voltage across the piezoelectric elements which causes the bimorph to bend back and forth at high rates. A medium is passed in a direction at least partly orthogonal to the direction of oscillation of the bimorph so that spot, rapidly sweeping across the surface of the medium, scans the surface. To write information on the medium, a source sufficiently intense, is modulated and applied to the fiber. To read information, a sufficiently intense source is continuously applied to the fiber and a detector used to pick up light returned from the medium surface.

Development of a low temperature MEMS process with a PECVD amorphous silicon structural layer

Abstract: Amorphous silicon (a-Si:H) deposited at 150 °C by plasma-enhanced chemical vapor deposition (PECVD) is investigated as a structural layer for low temperature microelectromechanical system (MEMS) fabrication. The process development of depositing thick a-Si:H films and the material characterization of the film stress and hydrogen content is presented. To demonstrate a MEMS application, bimorph thermal actuators incorporating a-Si:H and aluminum were designed and fabricated resulting in tip deflection of hundreds of microns. The PECVD film coverage of various sidewall structures was also studied by scanning electron microscopy. Our a-Si:H films formed a sidewall coverage angle of 80° with the substrate. Mechanical simulations relate this angle within the range of minimum stress and maximum deflection of the actuator. Our results indicate that amorphous silicon is as an attractive structural material offering a low thermal budget for post-processing and integration of MEMS devices with complementary metal-oxide–semiconductor technology.