The present invention relates to an acrylic foam composition comprising an acrylic polymer and an acrylic processing aid which exhibits increased flexibility characteristics over other types of foam compositions. The methods and devices of the invention employ labelled reagents which are either analyte analogs or complementary specific binding pair members for the analyte and a novel arrangement of capture zones comprising immobilized specific binding substances for either the analyte or the labelled reagent to effect bound from unbound labelled reagent as a function of analyte concentration. A valve element seals a supply port that connects the inlet passage to the common feed passage to eliminate dead space and form a near bore line seal. A second brace member is positioned between the first end and the second end. The bio-implantable identification device includes at least one memory configured to store a key, a receiver configured to receive an identification request, at least one processor configured to sign the identification request using the key stored in the at least one memory of the device, and a transmitter configured to transmit the signed request.