Mechanical memory
View Patent ↗A first-in-first-out (FIFO) microelectromechanical memory apparatus (also termed a mechanical memory) is disclosed. The mechanical memory utilizes a plurality of memory cells, with each memory cell having a beam which can be bowed in either of two directions of curvature to indicate two different logic states for that memory cell. The memory cells can be arranged around a wheel which operates as a clocking actuator to serially shift data from one memory cell to the next. The mechanical memory can be formed using conventional surface micromachining, and can be formed as either a nonvolatile memory or as a volatile memory.
1. A first-in-first-out (FIFO) microelectromechanical memory apparatus, comprising:
(a) a substrate;
(b) a plurality of memory cells located on the substrate, with each memory cell further comprising:
(i) a suspended beam capable of being bowed in either of two opposite directions substantially parallel to the plane of the substrate, with each direction of bowing of the suspended beam representing a different logic state, and
(ii) a data transfer beam extending outward from each suspended beam proximate to a midpoint thereof to transfer logic state information from one of the memory cells to an adjacent memory cell; and
(c) an input actuator to program the logic state of an input memory cell of the plurality of memory cells.
2. The apparatus of claim 1 wherein the input actuator comprises a thermal actuator or an electrostatic actuator.
3. The apparatus of claim 1 further comprising a clocking actuator to initiate the transfer of the logic state information from one of the memory cells to the adjacent memory cell.
4. The apparatus of claim 3 wherein the clocking actuator comprises a wheel having a plurality of cams extending outward from an edge of the wheel to push against a moveable end of each suspended beam to initiate the transfer of the logic state information from that suspended beam to an adjacent suspended beam.
5. The apparatus of claim 4 wherein the clocking actuator further comprises a micromotor operatively connected to rotate the wheel.
6. The apparatus of claim 3 further comprising means for sequentially reading out the logic state information from the plurality of memory cells.
7. The apparatus of claim 6 wherein the means for sequentially reading out the logic state information comprises a light source for generating light, and a photodetector for sensing a change in the intensity of the light reaching the photodetector as the light is blocked and unblocked by movement of the data transfer beam of a final memory cell as the logic state of the final memory cell is changed over time, with the photodetector producing an electrical output signal containing the logic state information.
8. The apparatus of claim 6 wherein the means for sequentially reading out the logic state information comprises a capacitor having at least one stationary capacitor plate and at least one moveable capacitor plate located proximate to the stationary capacitor plate, with the moveable capacitor plate being operatively connected to the data transfer beam of a final memory cell to change the capacitance of the capacitor in response to a change in the logic state of the final memory cell.
9. The apparatus of claim 1 wherein each memory cell includes a bending actuator operatively connected to one end of the suspended beam to initially bow the suspended beam and thereby program an initial logic state therein upon activation of the actuator, and to at least partially unbow the suspended beam and thereby erase any logic state therein upon deactivation of the actuator.
10. The apparatus of claim 9 wherein the actuator comprises a thermal actuator or an electrostatic actuator.
11. The apparatus of claim 1 wherein each memory cell includes a latch to capture and hold one end of each suspended beam to initially bow the suspended beam and thereby program an initial state therein.