Compositions and methods relate to gas generants used in inflatable restraint systems. In a conductor pattern CPA and a conductor pattern CPB arranged so as to run side by side with each other, the conductor pattern CPA is divided into a first portion P1 and a second portion P2, and the conductor pattern CPB is also divided into a first portion P1 and a second portion P2. Each probe includes a length of rigid coaxial conductor configured to define a sensing pin at one end.