An occlusion system for a tissue channel, the system comprising: a frame (110, 160, 310) comprising: (a)(i) a proximal structure (111, 161, 311) including proximal struts (114, 164, 314), (a)(ii) a distal structure (112, 162, 312) including distal struts (114, 164, 314), and (a)(iii) an intermediate structure (113, 163, 313) coupling the proximal struts to the distal struts; and a shape memory polymer, SMP, foam (120, 170, 320) that expands from an unactuated configuration to an actuated configuration; and a central member (140, 190, 340, 640, 1130), wherein the central member includes a backbone structure that is proximal to the intermediate structure, wherein (b)(i) the proximal and distal struts (114, 164, 314) include a shape memory material, (b)(ii) the proximal struts expand from a first proximal configuration to a second proximal configuration and the distal struts expand from a first distal configuration to a second distal configuration, (b)(iii) the second proximal configuration has a larger maximum outer diameter than the first proximal configuration and the second distal configuration has a larger maximum outer diameter than the first distal configuration, and (b)(iv) the SMP foam is, in the unactuated configuration, included within the proximal struts when the proximal struts are in the second proximal configuration; wherein (c)(i) the SMP foam has a length that extends from a proximal end of the SMP foam to a distal end of the SMP foam; and (c)(ii) the SMP foam is fixedly attached to the system along only a first portion of the length and is not fixedly attached to the system along a second portion of the length, characterized in that (d)(i) the first portion of the length is fixedly attached to the backbone structure; and (d)(ii) the second portion of the length is slideably coupled to the backbone structure, such that the second portion of the length may slide along the central member. a frame (110, 160, 310) comprising: (a)(i) a proximal structure (111, 161, 311) including proximal struts (114, 164, 314), (a)(ii) a distal structure (112, 162, 312) including distal struts (114, 164, 314), and (a)(iii) an intermediate structure (113, 163, 313) coupling the proximal struts to the distal struts; and a shape memory polymer, SMP, foam (120, 170, 320) that expands from an unactuated configuration to an actuated configuration; and a central member (140, 190, 340, 640, 1130), wherein the central member includes a backbone structure that is proximal to the intermediate structure, wherein (b)(i) the proximal and distal struts (114, 164, 314) include a shape memory material, (b)(ii) the proximal struts expand from a first proximal configuration to a second proximal configuration and the distal struts expand from a first distal configuration to a second distal configuration, (b)(iii) the second proximal configuration has a larger maximum outer diameter than the first proximal configuration and the second distal configuration has a larger maximum outer diameter than the first distal configuration, and (b)(iv) the SMP foam is, in the unactuated configuration, included within the proximal struts when the proximal struts are in the second proximal configuration; wherein (c)(i) the SMP foam has a length that extends from a proximal end of the SMP foam to a distal end of the SMP foam; and (c)(ii) the SMP foam is fixedly attached to the system along only a first portion of the length and is not fixedly attached to the system along a second portion of the length, characterized in that (d)(i) the first portion of the length is fixedly attached to the backbone structure; and (d)(ii) the second portion of the length is slideably coupled to the backbone structure, such that the second portion of the length may slide along the central member.