Abstract:
A system and method for determining humidity based on determination of an offset voltage shift are disclosed. In one embodiment, a system for determining humidity comprises an electromechanical device comprising a first layer, a second layer, and a dielectric between the two layers, wherein the dielectric is spaced apart from at least one of the first and second layers in an unactuated state of the electromechanical device, and wherein the dielectric contacts both the first and second layers in an actuated state of the electromechanical device, a voltage source configured to apply, between the first and second layers, one or more voltages, and a processor configured to control the voltage source, to determine an offset voltage shift based on the applied voltages, and to determine information regarding humidity about the device based on the offset voltage shift.

Description:
BACKGROUND 
     1. Field 
     The field of the invention relates to sensors configured to display a false-color image. 
     2. Description of the Related Technology 
     Electromechanical systems include devices having electrical and mechanical elements, actuators, transducers, sensors, optical components (e.g., mirrors, prisms, and/or lens), and electronics. Electromechanical systems can be manufactured at a variety of scales including, but not limited to, microscales and nanoscales. For example, microelectromechanical systems (MEMS) devices can include structures having sizes ranging from about a micron to hundreds of microns or more. Nanoelectromechanical systems (NEMS) devices can include structures having sizes smaller than a micron including, for example, sizes smaller than several hundred nanometers. Electromechanical elements may be created using deposition, etching, lithography, and/or other micromachining processes that etch away parts of substrates and/or deposited material layers or that add layers to form electrical and electromechanical devices. In the following description, the term MEMS device is used as a general term to refer to electromechanical devices, and is not intended to refer to any particular scale of electromechanical devices unless specifically noted otherwise. 
     One type of electromechanical systems device is called an interferometric modulator. As used herein, the term interferometric modulator or interferometric light modulator refers to a device that selectively absorbs, transmits, and/or reflects light using the principles of optical interference. In certain embodiments, an interferometric modulator may comprise a pair of conductive plates, one or both of which may be transparent and/or reflective in whole or part and capable of relative motion upon application of an appropriate electrical signal. In a particular embodiment, one plate may comprise a stationary layer deposited on a substrate and the other plate may comprise a metallic membrane separated from the stationary layer by an air gap. As described herein in more detail, the position of one plate in relation to another can change the optical interference of light incident on the interferometric modulator. Such devices have a wide range of applications, and it would be beneficial in the art to utilize and/or modify the characteristics of these types of devices so that their features can be exploited in improving existing products and creating new products that have not yet been developed. 
     SUMMARY 
     The system, method, and devices of the invention each have several aspects, no single one of which is solely responsible for its desirable attributes. Without limiting the scope of this invention, its more prominent features will now be discussed briefly. After considering this discussion, and particularly after reading the section entitled “Detailed Description” one will understand how the features of this invention provide advantages over other display devices. 
     In one aspect a sensor comprises a hermetically sealed cell at least partially defined by a first layer which is at least partially reflective and a second layer which is at least partially reflective and is positioned apart from the first layer and substantially parallel to the first layer. 
     In one aspect, a sensor comprises a first layer which is at least partially reflective, a second layer which is at least partially reflective and is positioned apart from the first layer and substantially parallel to the first layer, and a scaling material between the first and second layers, wherein the distance between the first and second layers is dependent on the size of the scaling material, and wherein the size of the scaling material is dependent on the concentration of a particular gas about the sensor. 
     In one aspect a sensor comprises a two-dimensional array of modulators, wherein each modulator comprises a first layer which is at least partially reflective and a second layer which is at least partially reflective and spaced apart from the first layer, and a proof mass attached to the two-dimensional array. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric view depicting a portion of one embodiment of an interferometric modulator display in which a movable reflective layer of a first interferometric modulator is in a relaxed position and a movable reflective layer of a second interferometric modulator is in an actuated position. 
         FIG. 2  is a system block diagram illustrating one embodiment of an electronic device incorporating a 3×3 interferometric modulator display. 
         FIG. 3  is a diagram of movable mirror position versus applied voltage for one exemplary embodiment of an interferometric modulator of  FIG. 1 . 
         FIG. 4  is an illustration of a set of row and column voltages that may be used to drive an interferometric modulator display. 
         FIGS. 5A and 5B  illustrate one exemplary timing diagram for row and column signals that may be used to write a frame of display data to the 3×3 interferometric modulator display of  FIG. 2 . 
         FIGS. 6A and 6B  are system block diagrams illustrating an embodiment of a visual display device comprising a plurality of interferometric modulators. 
         FIG. 7A  is a cross section of the device of  FIG. 1 . 
         FIG. 7B  is a cross section of an alternative embodiment of an interferometric modulator. 
         FIG. 7C  is a cross section of another alternative embodiment of an interferometric modulator. 
         FIG. 7D  is a cross section of yet another alternative embodiment of an interferometric modulator. 
         FIG. 7E  is a cross section of an additional alternative embodiment of an interferometric modulator. 
         FIG. 8A  is a cross section of a sensor including a hermetically sealed cell according to one embodiment. 
         FIG. 8B  is a cross section of the sensor of  FIG. 8A  exposed to increased pressure. 
         FIG. 8C  is a cross section of the sensor of  FIG. 8A  exposed to decreased pressure. 
         FIG. 9A  is a cross section of a sensor including a hermetically sealed cell according to another embodiment. 
         FIG. 9B  is a cross section of the sensor of  FIG. 9A  exposed to increased pressure. 
         FIG. 9C  is a cross section of the sensor of  FIG. 9A  exposed to decreased pressure. 
         FIG. 10  is a cross section of a sensor including a hermetically sealed cell within a package. 
         FIG. 11A  is a front view of a diving watch incorporating a pressure sensor. 
         FIG. 11B  is a front view of a diving mask incorporating a pressure sensor. 
         FIG. 12  is a cross section of an infrared radiation sensor and false-color imaging display. 
         FIG. 13A  is cross section of a sensor including a scaling material according to one embodiment. 
         FIG. 13B  is a cross section of the sensor of  FIG. 13A  exposed to an environment having an environmental parameter which decreases the size of the scaling material. 
         FIG. 13C  is a cross section of the sensor of  FIG. 13A  exposed to an environment having an environmental parameter which increases the size of the scaling material. 
         FIG. 14A  is a cross section of a sensor including a transparent scaling material according to one embodiment. 
         FIG. 14B  is a cross section of the sensor of  FIG. 14A  exposed to an environment having an environmental parameter which decreases the size of the transparent scaling material. 
         FIG. 14C  is a cross section of the sensor of  FIG. 14A  exposed to an environment having an environmental parameter which increases the size of the transparent scaling material. 
         FIG. 15A  is a cross section of a sensor including a scaling material according to another embodiment. 
         FIG. 15B  is a cross section of the sensor of  FIG. 15A  exposed to an environment having an environmental parameter which decreases the size of the scaling material. 
         FIG. 15C  is a cross section of the sensor of  FIG. 15A  exposed to an environment having an environmental parameter which increases the size of the scaling material. 
         FIG. 16  is a cross section of an accelerometer. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is directed to certain specific embodiments of the invention. However, the invention can be embodied in a multitude of different ways. In this description, reference is made to the drawings wherein like parts are designated with like numerals throughout. As will be apparent from the following description, the embodiments may be implemented in any device that is configured to display an image, whether in motion (e.g., video) or stationary (e.g., still image), and whether textual or pictorial. More particularly, it is contemplated that the embodiments may be implemented in or associated with a variety of electronic devices such as, but not limited to, mobile telephones, wireless devices, personal data assistants (PDAs), hand-held or portable computers, GPS receivers/navigators, cameras, MP3 players, camcorders, game consoles, wrist watches, clocks, calculators, television monitors, flat panel displays, computer monitors, auto displays (e.g., odometer display, etc.), cockpit controls and/or displays, display of camera views (e.g., display of a rear view camera in a vehicle), electronic photographs, electronic billboards or signs, projectors, architectural structures, packaging, and aesthetic structures (e.g., display of images on a piece of jewelry). MEMS devices of similar structure to those described herein can also be used in non-display applications such as in electronic switching devices. 
     As mentioned above, an interferometric modulator selectively absorbs, transmits, and/or reflects light using the principles of optical interference. In one embodiment, an interferometric modulator comprises two conductive layers capable of relative motion upon application of an appropriate electrical signal, described further below with respect to  FIGS. 1-7 . However, other forces may move the two layers with respect to each other, including but not limited to pressure applied to an array, acceleration applied to a mass, force due to thermal expansion, or a magnetic field applied to a current. 
     The reflective properties of an interferometric modulator are based, at least partially, on the distance between the first and second layers. Thus, the force applied to an interferometric modulator, be it electric, magnetic, or mechanical, alters the reflective properties of the device, such as the color or intensity of reflected light. A user could therefore determine the forces applied to the device simply by looking at the interferometric modulator. In one embodiment, an array of interferometric modulators displays a false-color image representative of the forces applied to various portions of the array. 
     One interferometric modulator display embodiment comprising an interferometric MEMS display element is illustrated in  FIG. 1 . In these devices, the pixels are in either a bright or dark state. In the bright (“on” or “open”) state, the display element reflects (or transmit) a large portion of incident visible light to a user. When in the dark (“off” or “closed”) state, the display element reflects (or transmit) little incident visible light to the user. Depending on the embodiment, the light reflectance properties of the “on” and “off” states may be reversed. MEMS pixels can be configured to reflect predominantly at selected colors, allowing for a color display in addition to black and white. 
       FIG. 1  is an isometric view depicting two adjacent pixels in a series of pixels of a visual display, wherein each pixel comprises a MEMS interferometric modulator. In some embodiments, an interferometric modulator display comprises a row/column array of these interferometric modulators. Each interferometric modulator includes a pair of reflective layers positioned at a variable and controllable distance from each other to form a resonant optical cavity with at least one variable dimension. In one embodiment, one of the reflective layers may be moved between two positions. In the first position, referred to herein as the relaxed position, the movable reflective layer is positioned at a relatively large distance from a fixed partially reflective layer. In the second position, referred to herein as the actuated position, the movable reflective layer is positioned more closely adjacent to the partially reflective layer. Incident light that reflects from the two layers interferes constructively or destructively depending on the position of the movable reflective layer, producing either an overall reflective or non-reflective state for each pixel. 
     The depicted portion of the pixel array in  FIG. 1  includes two adjacent interferometric modulators  12   a  and  12   b . In the interferometric modulator  12   a  on the left, a movable reflective layer  14   a  is illustrated in a relaxed position at a predetermined distance from an optical stack  16   a , which includes a partially reflective layer. In the interferometric modulator  12   b  on the right, the movable reflective layer  14   b  is illustrated in an actuated position adjacent to the optical stack  16   b.    
     The optical stacks  16   a  and  16   b  (collectively referred to as optical stack  16 ), as referenced herein, typically comprise of several fused layers, which can include an electrode layer, such as indium tin oxide (ITO), a partially reflective layer, such as chromium, and a transparent dielectric. The optical stack  16  is thus electrically conductive, partially transparent and partially reflective, and may be fabricated, for example, by depositing one or more of the above layers onto a transparent substrate  20 . In some embodiments, the layers are patterned into parallel strips, and may form row electrodes in a display device as described further below. The movable reflective layers  14   a ,  14   b  may be formed as a series of parallel strips of a deposited metal layer or layers (orthogonal to the row electrodes of  16   a ,  16   b ) deposited on top of posts  18  and an intervening sacrificial material deposited between the posts  18 . When the sacrificial material is etched away, the movable reflective layers  14   a ,  14   b  are separated from the optical stacks  16   a ,  16   b  by a defined gap  19 . A highly conductive and reflective material such as aluminum may be used for the reflective layers  14 , and these strips may form column electrodes in a display device. 
     With no applied voltage, the cavity  19  remains between the movable reflective layer  14   a  and optical stack  16   a , with the movable reflective layer  14   a  in a mechanically relaxed state, as illustrated by the pixel  12   a  in  FIG. 1 . However, when a potential difference is applied to a selected row and column, the capacitor formed at the intersection of the row and column electrodes at the corresponding pixel becomes charged, and electrostatic forces pull the electrodes together. If the voltage is high enough, the movable reflective layer  14  is deformed and is forced against the optical stack  16 . A dielectric layer (not illustrated in this Figure) within the optical stack  16  may prevent shorting and control the separation distance between layers  14  and  16 , as illustrated by pixel  12   b  on the right in  FIG. 1 . The behavior is the same regardless of the polarity of the applied potential difference. In this way, row/column actuation that can control the reflective vs. non-reflective pixel states is analogous in many ways to that used in conventional LCD and other display technologies. 
       FIGS. 2 through 5  illustrate one exemplary process and system for using an array of interferometric modulators in a display application. 
       FIG. 2  is a system block diagram illustrating one embodiment of an electronic device that may incorporate aspects of the invention. In the exemplary embodiment, the electronic device includes a processor  21  which may be any general purpose single- or multi-chip microprocessor such as an ARM, Pentium®, Pentium II®, Pentium III®, Pentium IV®, Pentium® Pro, an 8051, a MIPS®, a Power PC®, an ALPHA®, or any special purpose microprocessor such as a digital signal processor, microcontroller, or a programmable gate array. As is conventional in the art, the processor  21  may be configured to execute one or more software modules. In addition to executing an operating system, the processor may be configured to execute one or more software applications, including a web browser, a telephone application, an email program, or any other software application. 
     In one embodiment, the processor  21  is also configured to communicate with an array driver  22 . In one embodiment, the array driver  22  includes a row driver circuit  24  and a column driver circuit  26  that provide signals to a panel or display array (display)  30 . The cross section of the array illustrated in  FIG. 1  is shown by the lines  1 - 1  in  FIG. 2 . For MEMS interferometric modulators, the row/column actuation protocol may take advantage of a hysteresis property of these devices illustrated in  FIG. 3 . It may require, for example, a 10 volt potential difference to cause a movable layer to deform from the relaxed state to the actuated state. However, when the voltage is reduced from that value, the movable layer maintains its state as the voltage drops back below 10 volts. In the exemplary embodiment of  FIG. 3 , the movable layer does not relax completely until the voltage drops below 2 volts. There is thus a range of voltage, about 3 to 7 V in the example illustrated in  FIG. 3 , where there exists a window of applied voltage within which the device is stable in either the relaxed or actuated state. This is referred to herein as the “hysteresis window” or “stability window.” For a display array having the hysteresis characteristics of  FIG. 3 , the row/column actuation protocol can be designed such that during row strobing, pixels in the strobed row that are to be actuated are exposed to a voltage difference of about 10 volts, and pixels that are to be relaxed are exposed to a voltage difference of close to zero volts. After the strobe, the pixels are exposed to a steady state voltage difference of about 5 volts such that they remain in whatever state the row strobe put them in. After being written, each pixel sees a potential difference within the “stability window” of 3-7 volts in this example. This feature makes the pixel design illustrated in  FIG. 1  stable under the same applied voltage conditions in either an actuated or relaxed pre-existing state. Since each pixel of the interferometric modulator, whether in the actuated or relaxed state, is essentially a capacitor formed by the fixed and moving reflective layers, this stable state can be held at a voltage within the hysteresis window with almost no power dissipation. Essentially no current flows into the pixel if the applied potential is fixed. 
     In typical applications, a display frame may be created by asserting the set of column electrodes in accordance with the desired set of actuated pixels in the first row. A row pulse is then applied to the row  1  electrode, actuating the pixels corresponding to the asserted column lines. The asserted set of column electrodes is then changed to correspond to the desired set of actuated pixels in the second row. A pulse is then applied to the row  2  electrode, actuating the appropriate pixels in row  2  in accordance with the asserted column electrodes. The row  1  pixels are unaffected by the row  2  pulse, and remain in the state they were set to during the row  1  pulse. This may be repeated for the entire series of rows in a sequential fashion to produce the frame. Generally, the frames are refreshed and/or updated with new display data by continually repeating this process at some desired number of frames per second. A wide variety of protocols for driving row and column electrodes of pixel arrays to produce display frames are also well known and may be used in conjunction with the present invention. 
       FIGS. 4 and 5  illustrate one possible actuation protocol for creating a display frame on the 3×3 array of  FIG. 2 .  FIG. 4  illustrates a possible set of column and row voltage levels that may be used for pixels exhibiting the hysteresis curves of  FIG. 3 . In the  FIG. 4  embodiment, actuating a pixel involves setting the appropriate column to −V bias , and the appropriate row to +ΔV, which may correspond to −5 volts and +5 volts respectively. Relaxing the pixel is accomplished by setting the appropriate column to +V bias , and the appropriate row to the same +ΔV, producing a zero volt potential difference across the pixel. In those rows where the row voltage is held at zero volts, the pixels are stable in whatever state they were originally in, regardless of whether the column is at +V bias , or −V bias . As is also illustrated in  FIG. 4 , it will be appreciated that voltages of opposite polarity than those described above can be used, e.g., actuating a pixel can involve setting the appropriate column to +V bias , and the appropriate row to −ΔV. In this embodiment, releasing the pixel is accomplished by setting the appropriate column to −V bias , and the appropriate row to the same −ΔV, producing a zero volt potential difference across the pixel. 
       FIG. 5B  is a timing diagram showing a series of row and column signals applied to the 3×3 array of  FIG. 2  which will result in the display arrangement illustrated in  FIG. 5A , where actuated pixels are non-reflective. Prior to writing the frame illustrated in  FIG. 5A , the pixels can be in any state, and in this example, all the rows are at 0 volts, and all the columns are at +5 volts. With these applied voltages, all pixels are stable in their existing actuated or relaxed states. 
     In the  FIG. 5A  frame, pixels ( 1 , 1 ), ( 1 , 2 ), ( 2 , 2 ), ( 3 , 2 ) and ( 3 , 3 ) are actuated. To accomplish this, during a “line time” for row  1 , columns  1  and  2  are set to −5 volts, and column  3  is set to +5 volts. This does not change the state of any pixels, because all the pixels remain in the 3-7 volt stability window. Row  1  is then strobed with a pulse that goes from 0, up to 5 volts, and back to zero. This actuates the ( 1 , 1 ) and ( 1 , 2 ) pixels and relaxes the ( 1 , 3 ) pixel. No other pixels in the array are affected. To set row  2  as desired, column  2  is set to −5 volts, and columns  1  and  3  are set to +5 volts. The same strobe applied to row  2  will then actuate pixel ( 2 , 2 ) and relax pixels ( 2 , 1 ) and ( 2 , 3 ). Again, no other pixels of the array are affected. Row  3  is similarly set by setting columns  2  and  3  to −5 volts, and column  1  to +5 volts. The row  3  strobe sets the row  3  pixels as shown in  FIG. 5A . After writing the frame, the row potentials are zero, and the column potentials can remain at either +5 or −5 volts, and the display is then stable in the arrangement of  FIG. 5A . It will be appreciated that the same procedure can be employed for arrays of dozens or hundreds of rows and columns. It will also be appreciated that the timing, sequence, and levels of voltages used to perform row and column actuation can be varied widely within the general principles outlined above, and the above example is exemplary only, and any actuation voltage method can be used with the systems and methods described herein. 
       FIGS. 6A and 6B  are system block diagrams illustrating an embodiment of a display device  40 . The display device  40  can be, for example, a cellular or mobile telephone. However, the same components of display device  40  or slight variations thereof are also illustrative of various types of display devices such as televisions and portable media players. 
     The display device  40  includes a housing  41 , a display  30 , an antenna  43 , a speaker  45 , an input device  48 , and a microphone  46 . The housing  41  is generally formed from any of a variety of manufacturing processes as are well known to those of skill in the art, including injection molding, and vacuum forming. In addition, the housing  41  may be made from any of a variety of materials, including but not limited to plastic, metal, glass, rubber, and ceramic, or a combination thereof. In one embodiment the housing  41  includes removable portions (not shown) that may be interchanged with other removable portions of different color, or containing different logos, pictures, or symbols. 
     The display  30  of exemplary display device  40  may be any of a variety of displays, including a bi-stable display, as described herein. In other embodiments, the display  30  includes a flat-panel display, such as plasma, EL, OLED, STN LCD, or TFT LCD as described above, or a non-flat-panel display, such as a CRT or other tube device, as is well known to those of skill in the art. However, for purposes of describing the present embodiment, the display  30  includes an interferometric modulator display, as described herein. 
     The components of one embodiment of exemplary display device  40  are schematically illustrated in  FIG. 6B . The illustrated exemplary display device  40  includes a housing  41  and can include additional components at least partially enclosed therein. For example, in one embodiment, the exemplary display device  40  includes a network interface  27  that includes an antenna  43  which is coupled to a transceiver  47 . The transceiver  47  is connected to the processor  21 , which is connected to conditioning hardware  52 . The conditioning hardware  52  may be configured to condition a signal (e.g. filter a signal). The conditioning hardware  52  is connected to a speaker  45  and a microphone  46 . The processor  21  is also connected to an input device  48  and a driver controller  29 . The driver controller  29  is coupled to a frame buffer  28  and to the array driver  22 , which in turn is coupled to a display array  30 . A power supply  50  provides power to all components as required by the particular exemplary display device  40  design. 
     The network interface  27  includes the antenna  43  and the transceiver  47  so that the exemplary display device  40  can communicate with one or more devices over a network. In one embodiment the network interface  27  may also have some processing capabilities to relieve requirements of the processor  21 . The antenna  43  is any antenna known to those of skill in the art for transmitting and receiving signals. In one embodiment, the antenna transmits and receives RF signals according to the IEEE 802.11 standard, including IEEE 802.11(a), (b), or (g). In another embodiment, the antenna transmits and receives RF signals according to the BLUETOOTH standard. In the case of a cellular telephone, the antenna is designed to receive CDMA, GSM, AMPS or other known signals that are used to communicate within a wireless cell phone network. The transceiver  47  pre-processes the signals received from the antenna  43  so that they may be received by and further manipulated by the processor  21 . The transceiver  47  also processes signals received from the processor  21  so that they may be transmitted from the exemplary display device  40  via the antenna  43 . 
     In an alternative embodiment, the transceiver  47  can be replaced by a receiver. In yet another alternative embodiment, network interface  27  can be replaced by an image source, which can store or generate image data to be sent to the processor  21 . For example, the image source can be a digital video disc (DVD) or a hard-disc drive that contains image data, or a software module that generates image data. 
     Processor  21  generally controls the overall operation of the exemplary display device  40 . The processor  21  receives data, such as compressed image data from the network interface  27  or an image source, and processes the data into raw image data or into a format that is readily processed into raw image data. The processor  21  then sends the processed data to the driver controller  29  or to frame buffer  28  for storage. Raw data typically refers to the information that identifies the image characteristics at each location within an image. For example, such image characteristics can include color, saturation, and gray-scale level. 
     In one embodiment, the processor  21  includes a microcontroller, CPU, or logic unit to control operation of the exemplary display device  40 . Conditioning hardware  52  generally includes amplifiers and filters for transmitting signals to the speaker  45 , and for receiving signals from the microphone  46 . Conditioning hardware  52  may be discrete components within the exemplary display device  40 , or may be incorporated within the processor  21  or other components. 
     The driver controller  29  takes the raw image data generated by the processor  21  either directly from the processor  21  or from the frame buffer  28  and reformats the raw image data appropriately for high speed transmission to the array driver  22 . Specifically, the driver controller  29  reformats the raw image data into a data flow having a raster-like format, such that it has a time order suitable for scanning across the display array  30 . Then the driver controller  29  sends the formatted information to the array driver  22 . Although a driver controller  29 , such as a LCD controller, is often associated with the system processor  21  as a stand-alone Integrated Circuit (IC), such controllers may be implemented in many ways. They may be embedded in the processor  21  as hardware, embedded in the processor  21  as software, or fully integrated in hardware with the array driver  22 . 
     Typically, the array driver  22  receives the formatted information from the driver controller  29  and reformats the video data into a parallel set of waveforms that are applied many times per second to the hundreds and sometimes thousands of leads coming from the display&#39;s x-y matrix of pixels. 
     In one embodiment, the driver controller  29 , array driver  22 , and display array  30  are appropriate for any of the types of displays described herein. For example, in one embodiment, driver controller  29  is a conventional display controller or a bi-stable display controller (e.g., an interferometric modulator controller). In another embodiment, array driver  22  is a conventional driver or a bi-stable display driver (e.g., an interferometric modulator display). In one embodiment, a driver controller  29  is integrated with the array driver  22 . Such an embodiment is common in highly integrated systems such as cellular phones, watches, and other small area displays. In yet another embodiment, display array  30  is a typical display array or a bi-stable display array (e.g., a display including an array of interferometric modulators). 
     The input device  48  allows a user to control the operation of the exemplary display device  40 . In one embodiment, input device  48  includes a keypad, such as a QWERTY keyboard or a telephone keypad, a button, a switch, a touch-sensitive screen, a pressure- or heat-sensitive membrane. In one embodiment, the microphone  46  is an input device for the exemplary display device  40 . When the microphone  46  is used to input data to the device, voice commands may be provided by a user for controlling operations of the exemplary display device  40 . 
     Power supply  50  can include a variety of energy storage devices as are well known in the art. For example, in one embodiment, power supply  50  is a rechargeable battery, such as a nickel-cadmium battery or a lithium ion battery. In another embodiment, power supply  50  is a renewable energy source, a capacitor, or a solar cell, including a plastic solar cell, and solar-cell paint. In another embodiment, power supply  50  is configured to receive power from a wall outlet. 
     In some implementations control programmability resides, as described above, in a driver controller which can be located in several places in the electronic display system. In some cases control programmability resides in the array driver  22 . Those of skill in the art will recognize that the above-described optimization may be implemented in any number of hardware and/or software components and in various configurations. 
     The details of the structure of interferometric modulators that operate in accordance with the principles set forth above may vary widely. For example,  FIGS. 7A-7E  illustrate five different embodiments of the movable reflective layer  14  and its supporting structures.  FIG. 7A  is a cross section of the embodiment of  FIG. 1 , where a strip of metal material  14  is deposited on orthogonally extending supports  18 . In  FIG. 7B , the moveable reflective layer  14  of each interferometric modulator is square or rectangular in shape and attached to supports at the corners only, on tethers  32 . In  FIG. 7C , the moveable reflective layer  14  is square or rectangular in shape and suspended from a deformable layer  34 , which may comprise a flexible metal. The deformable layer  34  connects, directly or indirectly, to the substrate  20  around the perimeter of the deformable layer  34 . These connections are herein referred to as support posts. The embodiment illustrated in  FIG. 7D  has support post plugs  42  upon which the deformable layer  34  rests. The movable reflective layer  14  remains suspended over the gap, as in  FIGS. 7A-7C , but the deformable layer  34  does not form the support posts by filling holes between the deformable layer  34  and the optical stack  16 . Rather, the support posts are formed of a planarization material, which is used to form support post plugs  42 . The embodiment illustrated in  FIG. 7E  is based on the embodiment shown in  FIG. 7D , but may also be adapted to work with any of the embodiments illustrated in  FIGS. 7A-7C  as well as additional embodiments not shown. In the embodiment shown in  FIG. 7E , an extra layer of metal or other conductive material has been used to form a bus structure  44 . This allows signal routing along the back of the interferometric modulators, eliminating a number of electrodes that may otherwise have had to be formed on the substrate  20 . 
     In embodiments such as those shown in  FIG. 7 , the interferometric modulators function as direct-view devices, in which images are viewed from the front side of the transparent substrate  20 , the side opposite to that upon which the modulator is arranged. In these embodiments, the reflective layer  14  optically shields the portions of the interferometric modulator on the side of the reflective layer opposite the substrate  20 , including the deformable layer  34 . This allows the shielded areas to be configured and operated upon without negatively affecting the image quality. For example, such shielding allows the bus structure  44  in  FIG. 7E , which provides the ability to separate the optical properties of the modulator from the electromechanical properties of the modulator, such as addressing and the movements that result from that addressing. This separable modulator architecture allows the structural design and materials used for the electromechanical aspects and the optical aspects of the modulator to be selected and to function independently of each other. Moreover, the embodiments shown in  FIGS. 7C-7E  have additional benefits deriving from the decoupling of the optical properties of the reflective layer  14  from its mechanical properties, which are carried out by the deformable layer  34 . This allows the structural design and materials used for the reflective layer  14  to be optimized with respect to the optical properties, and the structural design and materials used for the deformable layer  34  to be optimized with respect to desired mechanical properties. 
       FIG. 8A  is a cross section of a sensor  800  including a hermetically sealed cell according to one embodiment. The hermetically sealed cell can be formed on a substrate, which can be made of glass, plastic, metal, semiconductors, or other suitable materials for supporting one or more cells. The sensor  800  includes a first layer  810  and a second layer  820  coupled together by a spacer  850  which surrounds a cavity  840  between the first layer  810  and the second layer  820 . Although the spacer  850  is only shown in two places in the cross section of  FIG. 8A , it is to be appreciated that the spacer  850  forms a closed shape between the first layer  810  and second layer  820 . The first layer  810 , second layer  820 , and spacer  850  define a hermetically sealed cell about the cavity  840 . Thus, the interior of the cavity  840  is separate and not in fluid communication with the air outside of the cavity  840 . The cavity  840  may be filled with a vacuum, air, helium, argon, xenon, or some other gas or combination of gases. 
     In one embodiment, the first layer  810  is at least partially reflective and partially transmissive and the second layer  820  is at least partially reflective. Thus, the cavity  840  can function as an interferometric cavity. In one embodiment, the cell inferometrically modulates at least one visible wavelength of light. In a particularly embodiment, the gap distance between the first and second layers is less than 3 mm, less than 2 mm, or less than 1 mm. The reflective properties of the sensor  800  depend, at least in part, on the gap distance between the first layer  810  and the second layer  820 . In one embodiment, the sensor reflects different wavelengths of light depending on the gap distance. Thus, the sensor appears as a different color depending on the gap distance. 
       FIG. 8B  is a cross section of the sensor  800  of  FIG. 8A  exposed to increased pressure. In  FIG. 8B , the sensor  800  is exposed to a pressure which is greater than the pressure to which the sensor  800  in  FIG. 8A  is exposed. In response to the increased pressure, the cavity  840  decreases volume to equalize the pressure inside and outside of the cavity  840 . Because the cavity  840  is hermetically sealed, the amount of air inside the cavity is fixed. Thus, as the volume of the cavity  840  decreases, the pressure increases in accordance with the ideal gas law. 
     In one embodiment, the first layer  810  is at least partially flexible and moves towards the second layer  820 , which is rigid. The first layer  810  may comprise a flexible portion  814  towards the periphery of the sensor, and a rigid portion  812  towards the center, such that the rigid portion  812  is substantially parallel with the second layer  820 . In another embodiment, the second layer  820  is at least partially flexible and moves towards the first layer  810 . 
     As the first layer  810  and second layer  820  move closer together, the gap distance is decreased and the reflective properties of the sensor  800  change. In particular, as the gap distance is decreased, the sensor  800  reflects shorter wavelengths of light. Thus, the color of the sensor  800  changes. For example, in one embodiment, the sensor  800  reflects predominantly yellow light at neutral pressure and reflects predominantly green light at increased pressure. 
       FIG. 8C  is a cross section of the sensor  800  of  FIG. 8A  exposed to decreased pressure. In  FIG. 8C , the sensor  800  is exposed to a pressure which is less than the pressure to which the sensor  800  in  FIG. 8A  is exposed. In response to the decreased pressure, the cavity  840  increases volume to equalize the pressure inside and outside of the cavity  840 . As the first layer  810  and second layer  820  move further apart, the gap distance is increased and the reflective properties of the sensor  800  change. In particular, as the gap distance is increased, the sensor  800  reflects longer wavelengths of light. Thus, the color of the sensor  800  changes. For example, in one embodiment, the sensor  800  reflects predominantly yellow light at neutral pressure and reflects predominantly red light at decreased pressure. 
     As mentioned above, the wavelength of light reflected by the sensor  800  is dependent on the gap distance between the first layer  810  and the second layer  820 . The gap distance is dependent on the volume of the cavity  840  between the first layer  810  and the second layer  820  and further, the volume of the cavity  840  is dependent on the pressure within the cavity  840 . However, the wavelength of light reflected by the sensor  800  is not only dependent on the pressure within the cavity  840 , but also the configuration of the cell. For example, at a constant pressure, an increase in volume at the periphery of the cell results in a decrease in volume towards the center of the cell. Thus, in one embodiment, the size of the spacer  850  is adjustable. By increasing the height of the spacer  850 , the volume at the periphery of the cell is increased and, thus, the volume at the center of the cell decreases by, e.g., motion of the rigid portion  812  of the first layer  810  towards the second layer  820 . Accordingly, an adjustable spacer  850  allows a user to preset a particular color with a particular pressure. When the pressure about the sensor  800  increases, the rigid portion  812  of the first layer  810  moves closer still towards the second layer  820 , resulting in the reflection of light of a shorter wavelength. In one embodiment, the spacer  850  includes a threaded top portion which twists on a matchingly threaded bottom portion. The threads may be fine, allowing adjustments of the size of the spacer  850  on the order of nanometers. 
       FIG. 9A  is a cross section of a sensor  900  including a hermetically sealed cell according to another embodiment. The sensor  900  includes a first layer  910 , a second layer  920 , and a third layer  930 . The first layer  910  and second layer  920  are coupled together by a first spacer  952  defining a first cavity  942  between the first layer  910  and the second layer  920 . The second layer  920  and third layer  930  are coupled together by a second spacer  954  which surrounds a second cavity  944  between the second layer  920  and the third layer  930 . The first spacer  952  may be permeable, such that the first cavity  942  between the first layer  910  and second layer  920  is not hermetically sealed. Although the second spacer  954  is only shown in two places in the cross section of  FIG. 9A , it is to be appreciated that the second spacer  954  forms a closed shape between the second layer  920  and third layer  930 . The second layer  920 , third layer  930 , and second spacer  954  define a hermetically sealed cell about the second cavity  944 . Thus, the air within the second cavity  944  is separate and not in fluid communication with the air outside of the second cavity  944 . 
     In one embodiment, the first layer  910  is at least partially reflective and partially transmissive and the second layer  920  is at least partially reflective. Thus, the first cavity  942  can function as an interferometric cavity. However, it is not necessarily a hermetically sealed interferometric cavity as is the cavity  840  of  FIG. 8A . The reflective properties of the sensor  900  depend, at least in part, on the gap distance between the first layer  910  and the second layer  920 . In one embodiment, the sensor  900  reflects different wavelengths of light depending on the gap distance. Thus, the sensor  900  appears as a different color depending on the gap distance. 
       FIG. 9B  is a cross section of the sensor  900  of  FIG. 9A  exposed to increased pressure. In  FIG. 9B , the sensor  900  is exposed to a pressure which is greater than the pressure to which the sensor  900  in  FIG. 9A  is exposed. The pressure in the first cavity  942 , which is not hermetically sealed, is equal to the pressure about the sensor  900  without any motion of the layers. However, because the second cavity  944  is hermetically sealed, in order to equalize the pressure in the first cavity  942  and the second cavity  944 , the second cavity  944  decreases volume. Because the second cavity  944  is hermetically sealed, the amount of air inside the cavity is fixed. Thus, as the volume of the cavity  944  decreases, the pressure increases in accordance with the ideal gas law, thereby equalizing the pressure. 
     In one embodiment, the second layer  920  is at least partially flexible and moves towards the third layer  930 , which is rigid. The second layer  920  may comprise a flexible portion  924  towards the periphery of the sensor, and a rigid portion  922  towards the center, such that the rigid portion  922  is substantially parallel with the first layer  910 . 
     As the second layer  920  moves further away from the first layer  910 , the gap distance of the first cavity  942  is increased and the reflective properties of the sensor  900  change. In particular, as the gap distance is increased, the sensor  900  reflects longer wavelengths of light. Thus, the color of the sensor  900  changes. For example, in one embodiment, the sensor  900  reflects predominantly yellow light at neutral pressure and reflects predominantly red light at increased pressure. Thus, the sensor  900  reflects longer wavelengths of light at increased pressure. In comparison, the sensor  800  of  FIG. 8A  reflects shorter wavelengths of light at increased pressure. 
       FIG. 9C  is a cross section of the sensor  900  of  FIG. 9A  exposed to decreased pressure. In  FIG. 9C , the sensor  900  is exposed to a pressure which is less than the pressure to which the sensor  900  in  FIG. 9A  is exposed. As described above with respect to  FIG. 9B , the pressure in the first cavity  942 , which is not hermetically sealed, is equal to the pressure about the sensor  900  without any motion of the layers. However, because the second cavity  944  is hermetically sealed, in order to equalize the pressure in the first cavity  942  and the second cavity  944 , the second cavity  944  increases volume. As the second layer  920  moves closer to the first layer  910 , the gap distance of the first cavity  942  is decreased and the reflective properties of the sensor  900  change. In particular, as the gap distance is decreased, the sensor  900  reflects shorter wavelengths of light. Thus, the color of the sensor  900  changes. For example, in one embodiment, the sensor  900  reflects predominantly yellow light at neutral pressure and reflects predominantly green light at decreased pressure. Thus, the sensor  900  reflects shorter wavelengths of light at decreased pressure. In comparison, the sensor  800  of  FIG. 8A  reflects longer wavelengths of light at decreased pressure. 
       FIG. 10  is a cross section of a sensor  1000  including a hermetically sealed cell within a package  1070 . The sensor  1000  includes a hermetically sealed cell defined, at least in part, by a first layer  1010  and a second layer  1020  coupled together by a spacer  1050  which surrounds an interferometric cavity  1040  between the first layer  1010  and the second layer  1020 . In another embodiment, the sensor  1000  includes an inverse-type interferometric modulator such as that illustrated and described above with respect to  FIG. 9A . Although only one cell is illustrated in  FIG. 10 , in one embodiment, the package houses multiple cells. In one embodiment, the package houses a two-dimensional array of cells. 
     The cell is surrounded by a package  1070  which protects the cell and includes a front plate  1072  and a back plate  1074 . In one embodiment, the front plate  1072  is a glass substrate. In one embodiment, the back plate  1074  is porous. Thus, the back plate  1074  can be air-permeable, water-permeable, or both. 
     When pressure about the sensor  1000  increases, the pressure in the area within the package  1070  and outside of the interferometric cavity  1040  equalizes as air permeates the back plate  1074  through the pores. The pressure inside the interferometric cavity  1040  is equalized by motion of the first layer  1040  towards the second layer  1020 . 
     In one embodiment, the package  1070  includes a membrane  1076  between the front plate  1072  and the back plate  1074 . The membrane  1076  is impermeable to air and water. The membrane  1076  seals the hermetically sealed cell in an outer cavity  1046 . The membrane  1076  may be particularly useful when the sensor  1000  is used to determine water pressure, as the membrane  1076  is exposed to water, which permeates the pores of the back plate  1074 , but the hermetically sealed cell is not. When water pressure about the sensor  1000  increases, the water pressure in the area between the back plate  1074  and the membrane  1076  equalizes as water permeates the back plate  1074  through the pores. The air pressure inside the outer cavity  1046  is equalized by motion of the membrane  1076  towards the front plate  1072 . The air pressure inside the interferometric cavity  1040  is similarly equalized by motion of the first layer  1010  towards the second layer  1020 . 
     The membrane  1076  can also be used to provide a lower limit on the pressure in the outer cavity  1046 . As pressure about the sensor  1000  is decreased, the pressure in the area between the back plate  1074  and the membrane  1076  equalizes as air or water permeates the back plate  1074  through the pores. The air pressure inside the outer cavity  1046  is equalized by motion of the membrane  1076  towards the back plate  1072 , thereby increasing the volume of the outer cavity  1046  and decreasing the pressure within the outer cavity  1046 . Once the membrane reaches the back plate  1074 , the volume of the outer cavity  1046  can expand no further, and thus, the pressure within the outer cavity  1046  can decrease no further. The pressure inside the interferometric cavity  1040  is equalized to the pressure in the outer cavity  1046  by motion of the first layer  1010  away from second layer  1020 . 
     In one embodiment, the package  1070  includes a porous midplate (not shown) between the membrane  1076  and the first layer  1010  to provide an upper limit on the pressure in the outer cavity  1046 . 
       FIG. 11A  is a front view of a diving watch  1100  incorporating a pressure sensor. The diving watch  1100  includes a display piece  1110  and a strap  1120 . At least a portion of the display piece  1110  comprises a pressure sensor  1112  including a substrate and a porous back plate which is positioned towards the front of the device. The pressure sensor  1112  is exposed to water when a user is submerged and is viewable by the user. Between the substrate and the back plate is a membrane sealing an outer cavity. Within the outer cavity is an inverse-type interferometric modulator such as sensor  900  described above with respect to  FIG. 9A , such that as the user descends to lower depths, the reflected wavelength of light changes from green to red. In another embodiment, an interferometric modulator such as sensor  800  described above with respect to  FIG. 8A  is within the package. 
       FIG. 11B  is a front view of a diving mask  1150  incorporating a pressure sensor. The diving mask  1150  includes a viewing window  1160 , a housing  1170  and a strap  1180 . At least a portion of the viewing window comprises a pressure sensor  1162  including a substrate and a porous back plate which is positioned toward the front of the device. The back plate is exposed to water when the user is submerged and the substrate is viewable by the user. Between the substrate and the back plate is a membrane sealing an outer cavity. Within the outer cavity and is an inverse-type interferometric modulator such as sensor  900  described above with respect to  FIG. 9A  having a partially reflective and partially transmissive first layer, a partially reflective second layer, and a third layer. In one embodiment, the second layer, third layer, back plate, and substrate are also at least partially transmissive. Thus, as light passes through the back plate, it is interferometrically modulated by the sensor before it passes through the substrate to the user&#39;s eyes. 
       FIG. 12  is a cross section of an infrared radiation sensor and false-color imaging display  1200 . The display  1200  includes a packaging  1270  including a front plate  1272  and a back plate  1274 . Within the packaging  1270  is a two-dimensional array of infrared radiation sensors  1201 . Each sensor  1201  includes a first layer  1210 , a second layer  1220 , and a third layer  1230 . The first layer  1210  and second layer  1220  are coupled together by a first spacer  1252  defining a first cavity  1242  between the first layer  1210  and the second layer  1220 . The second layer  1220  and third layer  1230  are coupled together by a second spacer  1254  which surrounds a second cavity  1244  between the second layer  1220  and the third layer  1230 . The first spacer  1252  may be permeable, such that the first cavity  1242  between the first layer  1210  and second layer  1220  is not hermetically sealed. In another embodiment, the first spacer  1242  hermetically seals the first cavity. Although the second spacer  1254  is only shown in two places per sensor  1201  in the cross section of  FIG. 12 , it is to be appreciated that the second spacer  1254  forms a closed shape for each sensor  1201  between the second layer  1220  and third layer  1230 . The second layer  1220 , third layer  1230 , and second spacer  1254  define a hermetically sealed cell about the second cavity  1244 . Thus, the air within the second cavity  1244  is separate and not in fluid communication with the air outside of the second cavity  1240 . 
     In one embodiment, the first layer  1210  is at least partially reflective and partially transmissive and the second layer  1220  is at least partially reflective. Thus, the first cavity  1242  can function as an interferometric cavity. As described above, the reflective properties of each the sensors  1201  depend, at least in part, on the gap distance between the first layer  1210  and the second layer  1220 . In one embodiment, each sensor  1201  reflects different wavelengths of light depending on the gap distance. Thus, each sensor  1201  appears as a different color depending on the gap distance. 
     In the embodiment illustrated in  FIG. 12 , the first layer  1210  of each sensor  1201  is attached to the front plate  1272 . In another embodiment, the third layer  1230  is attached to the back plate  1274  and the first layer  1210  is not attached to the front plate  1272 . 
     In one embodiment, the third layer  1230  is an infrared absorber. The display  1200  includes an infrared optical imaging system  1290  configured to image an infrared scene  1202  onto the third layers  1230  of the sensors  1201 . This causes the second cavity  1244  of each sensor  1201  to be heated to an extent determined by the intensity of the infrared radiation imaged onto that particular sensor  1201  by the optical imaging system  1290 . As the air inside the second cavity  1244  is heated, the volume of the second cavity  1244  is increased in accordance with the ideal gas law. This increase in volume of the second cavity  1244  results in a decrease in volume of the first cavity  1242 . Thus, the second layer  1220  is moved towards the first layer  1210 , changing the gap distance and changing the reflective properties of the sensor  1201 . Because the reflective properties of each sensor  1201  are changed in accordance with the amount of infrared radiation imaged onto the sensor  1201  by the optical imaging system  1290 , the two-dimension array of sensors  1201  will display a false-color image to a user  1204  by differentially reflecting incident light. 
     As described above, in one embodiment, the display  1200  includes an infrared optical imaging system  1290 , which may include one or more mirrors or lenses. In another embodiment, the third layer  1230  is exposed. The third layer may be placed and moved along a surface such that the display  1200  reveals “hot spots” as a false-color image. 
     The display  1200  can include heat removal channels to extract heat from the sensors  1201  at a steady rate so that the image will refresh. In one embodiment, the spacers  1252 ,  1254  are thermally conductive and conduct heat from the third layer  1230  to the front plate  1272 . One or more heat sinks, such as a thermally conductive grid, can be provided on the front plate  1272 . 
       FIG. 13A  is cross section of a sensor  1300  including a scaling material  1380  according to one embodiment. The sensor  1300  includes a first layer  1310  and a second layer  1320  separated by a scaling material  1380 . In one embodiment, the first layer  1310  is at least partially reflective and partially transmissive and the second layer  1320  is at least partially reflective, thereby defining an interferometric cavity  1340  between the first layer  1310  and the second layer  1320 . Unlike the sensor  800  in  FIG. 8A , the interferometric cavity  1340  is not necessarily hermetically sealed. 
     The scaling material  1380  changes size, e.g. expands or contracts, depending on environmental parameters of the environment to which the scaling material is exposed. For example, the scaling material  1380  may expand as temperature increases and contract as temperature decreases. As another example, the scaling material  1380  may expand as humidity increases and contract as humidity decreases. As another example, the scaling material  1380  may expand as pressure decreases and contract as pressure increases. As another example, the scaling material  1380  may expand as the concentration of a particular gas, such as O 2 , N 2 , SO, NO 3 , CO, or CO 2 , increases and contract as the concentration of the particular gas decreases. As another example, the scaling material  1380  may expand as radiation increases and contract as radiation decreases. Some, but not all, suitable scaling materials  1380  are described below following the discussion of  FIG. 15C . 
       FIG. 13B  is a cross section of the sensor  1300  of  FIG. 13A  exposed to an environment having an environmental parameter which decreases the size of the scaling material  1380 . In  FIG. 8B , the sensor  1300  is exposed to an environment having an environmental parameter of a value which decreases the size of the scaling material  1380  as compared to  FIG. 13A . As the first layer  1310  and second layer  1320  move closer together, the gap distance is decreased and the reflective properties of the sensor  1300  change. In particular, as the gap distance is decreased, the sensor  1300  reflects shorter wavelengths of light. Thus, the color of the sensor  1300  changes. For example, in one embodiment, the sensor  1300  reflects predominantly yellow light when exposed to an environment having an environmental parameter of a first value and reflects predominantly green light when exposed to an environment having an environmental parameter of a second value. 
       FIG. 13C  is a cross section of the sensor  1300  of  FIG. 13A  exposed to an environment having an environmental parameter which increases the size of the scaling material  1380 . In  FIG. 13C , the sensor  1300  is exposed to an environment having an environmental parameter of a value which increases the size of the scaling material  1380  as compared to  FIG. 13A . As the first layer  1310  and second layer  1320  move further apart, the gap distance is increased and the reflective properties of the sensor  1300  change. In particular, as the gap distance is increased, the sensor  1300  reflects longer wavelengths of light. Thus, the color of the sensor  1300  changes. For example, in one embodiment, the sensor  1300  reflects predominantly yellow light when exposed to an environment having an environmental parameter of first value and reflects predominantly red light when exposed to an environment having an environmental parameter of a second value. 
       FIG. 14A  is a cross section of a sensor  1400  including a transparent scaling material  1480  according to one embodiment. The sensor  1400  includes a first layer  1410  and a second layer  1420  separated by a transparent scaling material  1480 . In one embodiment, the scaling material  1480  is solid and couples the first layer  1410  and the second layer  1420 . In another embodiment, the scaling material  1480  is a fluid, such as a gas, a liquid, or a powder, and is contained between the first layer  1410  and the second layer  1420  by a spacer  1450 . In one embodiment, the first layer  1410  is at least partially reflective and partially transmissive and the second layer  1420  is at least partially reflective, thereby defining an interferometric cavity between the first layer  1410  and the second layer  1420 . As mentioned above, the scaling material  1480  changes size, e.g., expands or contracts, depending on environmental parameters of the environment to which the scaling material is exposed. Some, but not all, suitable scaling materials  1480  are described below following the discussion of  FIG. 15C . 
       FIG. 14B  is a cross section of the sensor  1400  of  FIG. 14A  exposed to an environment having an environmental parameter which decreases the size of the transparent scaling material  1480 . In  FIG. 14B , the sensor  1400  is exposed to an environment having an environmental parameter of a value which decreases the size of the scaling material  1480  as compared to  FIG. 14A . In one embodiment, the first layer  1410  is at least partially flexible and moves towards the second layer  1420 , which is rigid. The first layer  1410  may comprise a flexible portion  1414  towards the periphery of the sensor, and a rigid portion  1412  towards the center, such that the rigid portion  1412  is substantially parallel with the second layer  1420 . In another embodiment, the second layer  1420  is at least partially flexible and moves towards the first layer  140 . 
     As the first layer  1410  and second layer  1420  move closer together, the gap distance is decreased and the reflective properties of the sensor  1400  change. In particular, as the gap distance is decreased, the sensor  1400  reflects shorter wavelengths of light. Thus, the color of the sensor  1400  changes. For example, in one embodiment, the sensor  1400  reflects predominantly yellow light when exposed to an environment having an environmental parameter of a first value and reflects predominantly green light when exposed to an environment having an environmental parameter of a second value. 
       FIG. 14C  is a cross section of the sensor  1400  of  FIG. 14A  exposed to an environment having an environmental parameter which increases the size of the transparent scaling material  1480 . In  FIG. 14C , the sensor  1400  is exposed to an environment having an environmental parameter of a value which increases the size of the transparent scaling material  1480  as compared to  FIG. 14A . As the first layer  1410  and second layer  1420  move further apart, the gap distance is increased and the reflective properties of the sensor  1400  change. In particular, as the gap distance is increased, the sensor  1400  reflects longer wavelengths of light. Thus, the color of the sensor  1400  changes. For example, in one embodiment, the sensor  1400  reflects predominantly yellow light when exposed to an environment having an environmental parameter of a first value and reflects predominantly red light when exposed to an environment having an environmental parameter of a second value. 
     As mentioned above, in one embodiment, the transparent scaling material  1480  is solid and couples the first layer  1410  and the second layer  1420  and a separate spacer  1450  is unnecessary. Although in one embodiment, the first layer  1410  is partially flexible, in another embodiment, the first layer  1410  and second layer  1420  are both rigid and deposited on either side of the transparent scaling material  1480 . Accordingly, the sensor is a multi-layered, monolithic slab that grows thicker or thinner depending on the environmental parameters of the environment to which the sensor is exposed. Accordingly, the resonant wavelength and the wavelength of light reflected from the sensor changes depending on the environmental parameters of the environment to which the sensor is exposed. 
     As described above with respect to  FIG. 14A , in one embodiment, the scaling material  1480  changes size, e.g. expands or contracts, depending on environmental parameters of the environment to which the scaling material is exposed. In another embodiment of a sensor  1400 , the scaling material  1480  is replaced with a material for which the speed of light in the material changes depending on the environmental parameters of the environment to which the scaling material is exposed. 
       FIG. 15A  is a cross section of a sensor  1500  including a scaling material  1580  according to another embodiment. Unlike the scaling material  1480  in  FIG. 14A , the scaling material  1580  of the sensor  1500  is not necessarily transparent. The sensor  1500  includes a first layer  1510 , a second layer  1520 , and a third layer  1530 . The first layer  1510  and second layer  1520  are coupled together by a first spacer  1552  defining a first cavity  1542  between the first layer  1510  and the second layer  1520 . In one embodiment, the second layer  1520  and third layer  1530  are coupled together by a second spacer  1554  which surrounds a second cavity  1544  between the second layer  1520  and the third layer  1530  filed with a scaling material  1580 . In another embodiment, the scaling material  1580  couples the second layer  1520  and the third layer  1530 . The first spacer  1552  may be permeable, such that the first cavity  1542  between the first layer  1510  and second layer  1520  is not hermetically sealed. Although the second spacer  1554  is only shown in two places in the cross section of  FIG. 15A , it is to be appreciated that the second spacer  1554  can form a closed shape between the second layer  1520  and third layer  1530  to contain the scaling material  1580 . 
     In one embodiment, the first layer  1510  is at least partially reflective and partially transmissive and the second layer  1520  is at least partially reflective. Thus, the first cavity  1542  can function as an interferometric cavity. However, it is not necessarily a hermetically sealed interferometric cavity as is the cavity  840  of  FIG. 8A . The reflective properties of the sensor  1500  depend, at least in part, on the gap distance between the first layer  1510  and the second layer  1520 . In one embodiment, the sensor  1500  reflects different wavelengths of light depending on the gap distance. Thus, the sensor  1500  appears as a different color depending on the gap distance. 
       FIG. 15B  is a cross section of the sensor  1500  of  FIG. 15A  exposed to an environment having an environmental parameter which decreases the size of the scaling material  1580 . In  FIG. 15B , the sensor  1500  is exposed to an environment having an environmental parameter of value which decreases the size of the scaling material  1580  as compared to  FIG. 15A . In one embodiment, the second layer  1520  is at least partially flexible and moves towards the third layer  1530 , which is rigid. The second layer  1520  may comprise a flexible portion  1524  towards the periphery of the sensor, and a rigid portion  1522  towards the center, such that the rigid portion  1522  is substantially parallel with the first layer  1510 . 
     As the second layer  1520  moves further away from the first layer  1510 , the gap distance of the first cavity  1542  is increased and the reflective properties of the sensor  1500  change. In particular, as the gap distance is increased, the sensor  1500  reflects longer wavelengths of light. Thus, the color of the sensor  1500  changes. 
       FIG. 15C  is a cross section of the sensor  1500  of  FIG. 15A  exposed to an environment having an environmental parameter which increases the size of the scaling material  1580 . In  FIG. 15C , the sensor  1500  is exposed to an environment having an environmental parameter of a value which increases the size of the transparent scaling material  1580  as compared to  FIG. 15A . As the second layer  1520  moves closer to the first layer  1510 , the gap distance of the first cavity  1542  is decreased and the reflective properties of the sensor  1500  change. In particular, as the gap distance is decreased, the sensor  1500  reflects shorter wavelengths of light. Thus, the color of the sensor  1500  changes. 
     As mentioned above, the scaling material  1580  changes size, e.g. expands or contracts, depending on environmental parameters of the environment to which the scaling material is exposed. For example, the scaling material  1580  may expand as temperature increases and contract as temperature decreases. Many materials expand or contract at different temperatures according to their coefficient of thermal expansion. Some materials with very high coefficients of thermal expansion include gasoline, ethanol, rubber, water, mercury, PVC, and benzocyclobutene. Benzocyclobutene-based polymers can be used in manufacturing MEMS devices and, therefore, may be suitable for a MEMS sensor. Metals generally also have a high coefficient of thermal expansion, particularly lead, magnesium, aluminum, silver, copper, gold, nickel, iron, and platinum. In one embodiment, the scaling material  1580  has a higher coefficient of thermal expansion than that of the other components of the sensor  1500  such as the first layer  1510 , second layer,  1520 , third layer  1530 , or spacers  1552 ,  1554 . Generally, molybdenum, tungsten, glass, silicon, and quartz have lower coefficients of thermal expansion that the above-mentioned materials. 
     As another example, the scaling material  1580  may expand as pressure decreases and contract as pressure increases. Marshmallows, for example, expand when exposed to decreased pressure and contract when exposed to increased pressure. Other such materials include aerogels and polymer foams. 
     As another example, the scaling material  1580  may expand as the concentration of a particular gas, such as O 2 , N 2 , SO, NO 3 , H 2 O (humidity), CO, or CO 2 , increases and contract as the concentration of the particular gas decreases. Examples of such materials include cross-linked polyethylene oxide, hydrogels, hygroscopic aerogels, a polymeric material, thin poly (hydroxyethyl methacrylate) (PHEMA), poly (methyl methacrylate) (PMMA), and RTV silicone rubber. 
     As another example, the scaling material  1580  may expand as radiation increases and contract as radiation decreases. Examples of such a material include polymer networks containing azobenzene liquid-crystalline (LC) moieties, which are capable of changing their macroscopic shape when exposed to light. 
     In one embodiment, an infrared radiation sensor and false-color imaging display includes a packaging which houses a two-dimension array of sensors, such as described with respect to  FIG. 12 . Each sensor includes a first layer, second layer, and third layer, wherein the first layer and second layer are coupled together by a first spacer defining a first cavity and the second layer and third layer are coupled together by a second spacer defining a second cavity. In one embodiment, the second cavity houses a spacer material. 
       FIG. 16  is a cross section of an accelerometer  1600 . The accelerometer  1600  includes a packaging  1670  including a front plate  1672  and a back plate  1674 . Within the packaging  1670  is a two-dimensional array of motion sensors  1601 . Each sensor  1601  includes a first layer  1610  and a second layer  1620  coupled together by a spacer  1650  defining a cavity  1640  between the first layer  1610  and the second layer  1620 . The spacer  1652  may be permeable, such that the cavity  1640  between the first layer  1610  and second layer  1620  is not hermetically sealed. In another embodiment, the spacer  1640  hermetically seals the first cavity. 
     In one embodiment, the first layer  1610  is at least partially reflective and partially transmissive and the second layer  1620  is at least partially reflective. Thus, the cavity  1640  can function as an interferometric cavity. As described above, the reflective properties of each the sensors  1601  depend, at least in part, on the gap distance between the first layer  1610  and second layer  1620 . In one embodiment, each sensor  1601  reflects different wavelengths of light depending on the gap distance. Thus, each sensor  1601  appears as a different color depending on the gap distance. 
     In one embodiment, the second layer  1620  of each sensor  1601  is attached to a proof mass  1692  via a protrusion  1694 . In one embodiment, the protrusions  1694  are elastic. In another embodiment, the protrusions  1694  are elastic and different protrusions  1694  have different spring constants. The accelerometer  1600  may be firmly attached to a body of interest, such as a vehicle. When the accelerometer  1600  moves or experiences other acceleration, the force of the proof mass  1692  moves the second layer  1620  either towards or away from the first layer  1610 , changing the gap distance and changing the reflective properties of the sensor  1601 . Because the reflective properties of each sensor  1601  are changed in accordance with the amount of force applied to the second layer  1620  by the inertia of the proof mass  1692 , the two-dimension array of sensors  1601  will display a false-color image to a user by differentially reflecting incident light. 
     It is also to be recognized that, depending on the embodiment, the acts or events of any methods described herein can be performed in other sequences, may be added, merged, or left out altogether (e.g., not all acts or events are necessary for the practice of the methods), unless the text specifically and clearly states otherwise. 
     While the above description points out certain novel features of the invention as applied to various embodiments, the skilled person will understand that various omissions, substitutions, and changes in the form and details of the device or process illustrated may be made without departing from the scope of the invention. Therefore, the scope of the invention is defined by the appended claims rather than by the foregoing description. All variations coming within the meaning and range of equivalency of the claims are embraced within their scope.