Safety and arming device using cellulose-based sensor/actuator

A safety and arming device comprising:

• a housing;
• first and second portions of an explosive train fixably supported in said housing, said first and second portions being operably separated from one another;
• a third portion of said explosive train movably mounted in said housing, said third portion fixable in a first position wherein said first and second portions remain operably separated from one another, said third portion movable to a second position wherein said first and second portions are operably coupled to one another via said third portion;
• a water sensor/actuator coupled to said third portion, said water/sensor actuator including
• i) a water permeable housing;
• ii) a plug of dry and compressed fibrous cellulosic material having a powder material thereon and mixed therewith, said plug being compressed along an axis thereof and fitted in a portion of said housing adjacent one end thereof;
• iii) said cellulosic material having anisotropic moisture-absorbing properties wherein dried-in strain of said cellulosic material is greatest along said axis;
• iv) said powder material being inert with respect to said cellulosic material and initiating a chemical reaction when exposed to water, wherein a product of said chemical reaction is water;
• and
• v) a piston fitted in said housing adjacent said plug and coupled to said third portion, wherein immersion of said water permeable housing in water causes expansion of said plug and corresponding movement of said piston to move said third portion to said second position.