Filter media, such as electret-containing filtration media for filtering gas streams (e.g., air), are described herein. In some embodiments, the filter media may be designed to have desirable properties such as stable filtration efficiency over the lifetime of the filter media, increased normalized gamma, relatively low pressure drop (i.e. resistance), and/or relatively low basis weight. In certain embodiments, the filter media may be a composite of two or more types of fiber layers where each layer may be designed to enhance its function without substantially negatively impacting the performance of another layer of the media. For example, one layer of the media may be designed to have a relatively low basis weight and/or a relatively high air permeability, and another layer of the media may be designed to have stable filtration efficiency and/or a relatively high efficiency throughout the filter media's lifetime. The filter media described herein may be particularly well-suited for applications that involve filtering gas streams (e.g., face masks, cabin air filtration, vacuum filtration, room filtration, furnace filtration, respirator equipment, residential or industrial HVAC filtration, high-efficiency particulate arrestance (HEPA) filters, ultra-low particular air (ULPA) filters, medical equipment), though the media may also be used in other applications.

A variable capacitor device and a method of preparation thereof, wherein the variable capacitor device comprises a shape-memory polymer in its dielectric layer, wherein the shape-memory polymer determines the thickness of the dielectric layer, thereby causing the capacitance of the variable capacitor device to be tuned. Various embodiments of the variable capacitor device and the method of preparing said capacitor have also been provided.

Embodiments of an electroentropic memory device comprising an array of electroentropic storage devices (EESDs) are disclosed, as well as methods of making and using the electroentropic memory device. The memory device includes a plurality of address lines arranged in rows to select a row of the EESDs and a plurality of data lines arranged in columns to select a column of the EESDs, wherein each EESD is coupled in series between an address line connected to one side of the EESD and a data line connected to an opposing side of the EESD. The memory device may have a stacked architecture with multiple layers of address lines, data lines, and EESDs. The disclosed electroentropic memory devices are operable in ROM and RAM modes. EESDs in the disclosed electroentropic memory devices may include from 2-4096 logic states and/or have a density from 0.001 kb/cm.sup.3 to 1024 TB/cm.sup.3.

Embodiments of an electroentropic memory device comprising an array of electroentropic storage devices (EESDs) are disclosed, as well as methods of making and using the electroentropic memory device. The memory device includes a plurality of address lines arranged in rows to select a row of the EESDs and a plurality of data lines arranged in columns to select a column of the EESDs, wherein each EESD is coupled in series between an address line connected to one side of the EESD and a data line connected to an opposing side of the EESD. The memory device may have a stacked architecture with multiple layers of address lines, data lines, and EESDs. The disclosed electroentropic memory devices are operable in ROM and RAM modes. EESDs in the disclosed electroentropic memory devices may include from 2-4096 logic states and/or have a density from 0.001 kb/cm.sup.3 to 1024 TB/cm.sup.3.

A memory cell includes: a polarizable member including an electret to store a plurality of bits; a thermal electrode to heat the polarizable member; and a program electrode opposing the thermal electrode to program the polarizable member in a bit comprising a polarized state or a non-polarized state, the polarizable member being interposed between the thermal electrode and the program electrode. A random access memory includes: a plurality of addressable memory cells, the memory cell including: a thermal electrode; a program electrode opposing the thermal electrode; a polarizable member interposed between the thermal electrode and the program electrode, the polarizable member including an electret to store a plurality of bits.

A memory cell includes: a polarizable member including an electret to store a plurality of bits; a thermal electrode to heat the polarizable member; and a program electrode opposing the thermal electrode to program the polarizable member in a bit comprising a polarized state or a non-polarized state, the polarizable member being interposed between the thermal electrode and the program electrode. A random access memory includes: a plurality of addressable memory cells, the memory cell including: a thermal electrode; a program electrode opposing the thermal electrode; a polarizable member interposed between the thermal electrode and the program electrode, the polarizable member including an electret to store a plurality of bits.

An electret includes a substrate, and an electret layer formed on a surface of the substrate. The electret layer is an inorganic dielectric layer that has been electrically charged. The inorganic dielectric layer includes an outer layer and an inner layer that are stacked in a thickness direction of the substrate. The outer layer contains a first inorganic dielectric material as a main component which is a composite metal compound including different metal elements and has a bandgap energy of 3 eV or more. At least one of the different metal elements being a trivalent metal element. The inner layer contains a second inorganic dielectric material as a main component which is different from the first inorganic dielectric material.