1. A metal adsorbent fiber comprising a polyamine polymer which has repeating units of ethyleneimine and N-carboxy-methylated ethyleneimine represented by the following formula (1) and in which the average molecular weight of polyethyleneimine forming a chain frame is 600 to 150,000
wherein n represents a positive integer and m represents a positive integer; the polyamine polymer being incorporated into a cellulose fiber by incorporating the polyamine polymer into a solution of a raw material for the cellulose fiber to form a spinning solution and forming the spinning solution into a fiber by wet blend-spinning.
2. The metal adsorbent fiber according to claim 1, characterized in that an amount of the polyamine polymer blended into the raw material for the cellulose is 1-30 weight percent.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An actuator device, comprising:
a stack of piezoelectric-ferroelectric active layers separated by surface electrodes, wherein at least a few of said surface electrodes are independently addressable such that at least two active layers are biasable by different voltages; and
a voltage source and controller being in electrical communication with said at least few surface electrodes and configured to generate said voltages, wherein said voltages induce a nonlinear ferroelectric effect on at least one of said layers.
2. A method, comprising applying at least two different voltages to an actuator device which comprises a stack of piezoelectric-ferroelectric active layers separated by surface electrodes, such that said at least two voltages respectively bias at least two different active layers, and induce a nonlinear ferroelectric effect on at least one of said layers.
3. The method according to claim 1, wherein said voltages inducing said nonlinear ferroelectric effect are applied momentarily.
4. The device according to claim 1, wherein at least one layer is applied by a voltage inducing a nonlinear ferroelectric effect in said layer, and at least one layer is applied by a voltage inducing a linear inverse piezoelectric effect in said layer.
5. The device according to claim 4, wherein said voltage inducing said nonlinear ferroelectric effect is applied momentarily, and said voltage inducing said linear inverse piezoelectric effect is applied continuously.
6. The device according to claim 4, wherein a number of layers applied by said voltage inducing said linear inverse piezoelectric effect is selected so as to compensate a minimal discontinuous displacement generated by said nonlinear ferroelectric effect.
7. The device according to claim 1, further comprising a loop control unit for controlling voltages applied to induce a linear inverse piezoelectric effect in response to displacements generated by a nonlinear ferroelectric effect.
8. The device according to claim 4, further comprising controlling voltages applied to induce said linear inverse piezoelectric effect according to displacements generated by said nonlinear ferroelectric effect.
9. The device according to claim 7, wherein said displacements are sensed by an external sensor configured to sense said displacements.
10. The device according to claim 7, wherein said displacements are sensed by at least one piezoelectric-ferroelectric layer which is part of the stack and which is not electrically biased during said sensing.
11. The device according to claim 1, wherein the actuator device further comprises a prestressing element positioned in physical contact with said layers and selected to apply mechanical stress on said layers.
12. The device according to claim 1, wherein said stack of piezoelectric-ferroelectric active layers is interposed between a top edge plate and a bottom edge plate, and wherein the actuator device further comprises a prestressing element positioned in physical contact with at least one of said edge plates and selected to apply mechanical stress on said plate.
13. The device according to claim 11, wherein said prestressing element is shaped as a bar introduced along a thickness direction of said stack through bores formed in said layers and said surface electrodes.
14. The device according to claim 11, wherein said prestressing element is made of a material which is elastic under a characteristic deformation range of said piezoelectric-ferroelectric layers.
15. The device according to claim 11, wherein said prestressing element is selected to apply on said layers a stress within a predetermined range of stresses defined between an upper bound and a lower bound, said upper bound corresponding to a polarized domain state of said layers and said lower bound corresponding to a depoled domain state of said layers.
16. The device according to claim 1, wherein said stack is electrically partitioned to a plurality of sub-stacks of piezoelectric-ferroelectric layers in a manner such that at least two sub-stacks are electrically decoupled, but for each sub-stack all surface electrodes of said sub-stack are electrically coupled.
17. The device according to claim 16, wherein at least a few sub-stacks have equal number of layers.
18. The device according to claim 16, wherein at least a few sub-stacks have different numbers of layers.
19. The device according to claim 16, wherein said plurality of sub-stacks comprises N sub-stacks each having a different number of layers which equals 2k, k being an integer satisfying k\u2266N.
20. A system, comprising an actuatable device and the actuator device according to claim 1.
21. The system of claim 20, wherein said actuatable device comprises at least one of an optical alignment device, a pump injector, an interferometric dilatometer, a deformable mirror, a deformable optical grid, a microscope stage, a guide device, a cutting device, a valve, a VTR head, a swing CCD image sensor, a micro-angle adjusting device, a micro-angle adjusting device, an inkjet head, a dot-matrix printer head, a relay, an ultrasound generator, an aerodynamic steering wing, a rotor blade, a welding device, a suspension device, a vibration dumping system, a parallel robotic system, a hard disk drive head supporter arm, a nanofocusing Z-Drive, an optic fiber, and a switch.
22. The method of claim 2, wherein said at least two voltages comprise a first voltage and a second voltage and wherein said first voltage biases a single active layer.
23. A method, comprising applying to an actuator device voltage at sufficient amount so as to generate displacement in said actuator device, wherein said actuator device comprises a stack of piezoelectric-ferroelectric active layers separated by surface electrodes, wherein at least a few of said surface electrodes are independently addressable, and wherein said voltage is applied such as to induce a nonlinear ferroelectric effect on at least one of said layers.