Abstract: A deep insert, inflatable hearing protection earplug is provided that is easy for an untrained user to insert correctly, reliably providing high acoustic attenuation and remaining both secure and comfortable for long durations in a human ear. The earplug comprises a soft elastomer shell that forms a sealed volume filled with an inert fluid. The earplug can comprise a slender, flexible stem that is easily insertable into the ear canal when deflated. The proximal end of the earplug can be situated outside the ear canal, within the concha of the ear, and incorporates a bulb with a hemispherical, bistable cap. After inserting the shaft of the earplug into the ear canal, the wearer applies force with a finger to invert the cap, which transitions elastically from a convex to a concave external geometry, displacing a fixed volume of fluid to inflate a sheath that forms the outer covering of the stem, filling and sealing the ear canal.

Abstract: Systems and methods for storing fluid and sensing volume are described. In some embodiments, a system may include a container having an internal volume that is configured to change as fluid enters or exits the container, a first loop disposed on a first side of the container, and a second loop disposed on a second side of the container. A first current traveling through one of the first loop and the second loop may induce a second current in the other of the first loop and the second loop, and a magnitude of the second current may vary based on changes in the internal volume of the container.

Abstract: Systems and methods for storing fluid are described. In some embodiments, a system may include a container having an internal volume that is configured to change as fluid enters or exits, a first shell component, and a second shell component. The first shell component may limit an expansion of the container in a first direction, and the second shell component may limit the expansion of the container in a second direction that is opposite the first direction.

Abstract: A deep insert, inflatable hearing protection earplug is provided that is easy for an untrained user to insert correctly, reliably providing high acoustic attenuation and remaining both secure and comfortable for long durations in a human ear. The earplug comprises a soft elastomer shell that forms a sealed volume filled with an inert fluid. The earplug can comprise a slender, flexible stem that is easily insertable into the ear canal when deflated. The proximal end of the earplug can be situated outside the ear canal, within the concha of the ear, and incorporates a bulb with a hemispherical, bistable cap. After inserting the shaft of the earplug into the ear canal, the wearer applies force with a finger to invert the cap, which transitions elastically from a convex to a concave external geometry, displacing a fixed volume of fluid to inflate a sheath that forms the outer covering of the stem, filling and sealing the ear canal.