Researchers from Purdue University have proposed a new search for alien messages, not by scanning radio frequencies, but by looking for artificial patterns of neutrino pulses ('NU-SETI'). They note that since neutrinos are weakly interacting, any signal carried by a neutrino beam is "less likely to be distorted en route to Earth than would be the case for an electromagnetic signal":
In searching for SETI signals carried by neutrinos, there are at least two classes of signals that might be accessible to us. We start by recognizing that we already have the capability of generating pulsed neutrino beams at Fermilab, starting from pulsed proton beams. Specifically a pulsed beam was sent over a distance of 0.66 miles at an effective bit rate of 0.1 bits/sec, and was received with a detection accuracy of 99%. If we assume an advanced civilization can do somewhat better, then we can search for “universal” strings of pulses, say, those characterizing prime numbers 1,2,3,5,7,… The other class of signals would be those specific neutrino signals associated with an advanced civilization running exclusively on fission or fusion sources all of which produce characteristic neutrino signals.
It's all well and good to propose these things, but how viable is the search in real life given the equipment and time required? The researchers note that their proposed NU-SETI system would be "a scalable array of individual sites spread over the world", each looking for the signature decay rate of specific radioactive sources; each of those sites would cost approximately $20,000 to set up, so 1000 worldwide sites would cost $20million.
While this sounds like a non-starter based on the costs alone - especially considering how difficult it has been for regular SETI to raise funds over the years - the researchers involved point out that NU-SETI might happily be funded by "sectors sensitive to the effects of solar storms such as electric power companies and the military", as the data collected could simultaneously be used to predict solar storms and thus mitigate their effects. In that case, $20million seems like a bargain (as compared to, say, losing a satellite to an unexpected solar storm).