Self-supported chitosan-based proton-conducting membranes were used as both flexible substrates and gate dielectrics for paste-type TFTs with low-voltage operation and logic function.
This paper presents the possibility of piezoelectric RF-MEMS switches for low voltage operation. The switches we fabricated consist of micro-cantilevers using PZT thin films with the length of 490 μm and the width of 87 μm. The cantilevers are actuated as unimorph actuators that can be deflected by applying voltage between upper and lower electrodes. We could obtain large tip deflection of 3 μm even at the low voltage of 5.0V, which is well compatible with conventional IC drivers. This result indicates that the RF-MEMS switches using piezoelectric PZT thin films is advantageous to the low voltage switching devices in RF components compared with conventionally proposed electrostatic ones.
Ionomeric polymers are a class of electromechanical transducer consisting of an ionomeric substrate with metal-plated electrodes. Application of a low voltage (< 5 V) across the thickness of the membrane produces controllable strain. The advantage of ionomeric polymers compared to other types of electromechanical transducers (e.g. piezoelectric polymers) is low-voltage operation, high strain capability, and high sensitivity in charge mode. Two of the primary limitations of ionomeric polymers for electromechanical transducers are unstable operation in air and solvent breakdown at low voltage. This work focuses on overcoming these limitations through the development of an ionic liquid-ionomeric composite with a tailored electrode composition that maximizes strain output. It is becoming clear that charge accumulation at the polymer-electrode interface is the key to producing high strain in ionomeric polymer transducers. In this work we combine a previously developed process for incorporating ionic liquids into ionomer membranes with a new method for tailoring the electrode composition. The electrode composition is studied as a function of the surface-to-volume ratio and conductivity of the metal particulates. Results demonstrate that the surface-to-volume ratio of the metal particulate is critical to increasing the capacitance of the transducer. Increased conductivity of the metal particulates produces improved response at higher frequencies (> 10 Hz) but this effect is small compared to the increase in strain produced by maximizing the capacitance. Increasing capacitance produces a transducer that is able to achieve > 2% strain at voltage levels of +/- 3 V.
AbstractPZT thin films with a thickness of 70 nm were successfully fabricated using a modified solution combined with PbTiO3 seed layer. Throughout various approaches, we found that the microstructure of PZT thin film plays an important role in determining the electrical properties such as hysteretic properties and leakage currents, particularly when the thickness is below 100 nm. We modified the precursor system to improve the microstructure in PZT thin film. In addition, we also adopted a thin PbTiO3 seed layer to enhance the initial nucleation density. Finally, we could obtain good electric properties similar to those obtained from 240 nm thick PZT film. The hysteretic properties is excellent enough to operate at a low voltage (2V) for a high density FRAM application.
Ionic Liquid Containing Block Copolymer Dielectrics: Designing for High-Frequency Capacitance, Low-Voltage Operation, and Fast Switching Speeds