@rick merritt "military developers working on spray on films to ID terrorist"
Luckily there are also many non-military applications of spray-on electronics, from the exotic like adding the sense of touch to a robot's skin, to the practical, such as spraying-on solar cells for the backside of curtains to generate electricity. In fact, by using an ink-jet printer to do the spraying almost any current electronic circuits can be sprayed on (in principle, although there are several years of development ahead to realize these dreams).
The ability to spray circuits onto flexible substrates will enable many of the ubiquitous computing applications that we've been hearing about for years. If the system is being used to produce inexpensive curcuits for mass applications what dimension of circuit elements would be recommended? Presumably wider traces would provide some redundancy for any flaws in the spraying process or damage when the substrate was flexed. There are many simple circuits that could be implemented first (RFID chips, product expiration date sensors, alarms) before worrying about implementing complex microprocessors on flexible media.