Abstract: This document provides medical device systems and methods for obtaining tissue samples. For example, this document provides medical device systems and methods for transbronchial needle biopsy tissue acquisition. In some cases, a needle biopsy system includes an actuator device, an outer needle with a lumen therethrough, and an inner needle at least partially disposed within the lumen. The outer needle can extend distally from the actuator device. A distal tip of the inner needle can be capable of being fully disposed within the lumen. The inner needle can extend distally from the actuator device. The actuator device can be configured to translate the outer needle proximally and distally. The actuator device can be configured to translate the inner needle proximally and distally independently of the outer needle.

Abstract: Pressure-dependent anisotropic behavior is provided by a size selective separation membrane system having two successive porous layers. The first layer is a soft, elastic, effectively porous material, and the second layer is a substantially rigid porous material. When positive pressure presses the first layer against the second layer, the second layer serves as a rigid support, and the first layer is compressed to reduce its effective pore size. The first layer material is characterized by sufficient compressibility, that, when a pressure differential of 100 psi is applied across the thickness of the system, the effective flow rate is reduced by a factor of at least 20 compared to the flow rate when 100 psi is exerted in the opposite direction.