Micro-vias that are conventionally used for vertical connections in wire or circuit boards may be used for an entirely different purpose; the micro-vias may be used in the creation of solder joints to initiate the controlled formation of voids that increase the reliability of the solder joints. Consequently, the present invention can detect voltage in a stable condition with low power consumption. In some embodiments, for example, the invention provides alicyclic diaza compounds for phototherapeutic methods having a photolabile N\u2014N bond that undergoes photoactivated cleavage to produce reactive species, such as radicals, ions, etc.