Various devices are provided for allowing multiple surgical instruments to be inserted through a single surgical access device at variable angles of insertion, allowing for ease of manipulation within a patient’s body while maintaining insufflation. Conductive patterns within channels on the substrate provide interconnects that are isolated by the channel sides. An adhesive arrangement for such fiber composite components is also disclosed. The processor is programmed to process the sensor measurements to identify one or more characteristics in the measurements that can indicate the nature of the fluid being measured and thereby determine the location of the interface. Alternatively, these actions may be accomplished using a spatio-temporally varying filter. In particular, small RNA is separated and isolated from large RNA, DNA, proteins, and other macromolecules in the biological sample.