The full name of the device is a Psychokinetic Energy Meter, so named because its function is to detect the amounts of said energy and to direct the user to its location.
The design of the device is a small screen, mounted on a handle, which has a pair of sensor ‘wings’ protruding from either side. These wings have lights along their length, and will flash and extend as the meter closes in on the source of a P.K.E. signature. Much like a metaphysical Dowsing Rod, the meter will begin to buzz more and more in response to approaching a source of P.K. Energy. Once at the source of the energy, the wings will extend to their fullest length and the meter will buzz noticeably at a higher pitch.
The meters are also apparently the oldest equipment of the Ghostbusters. It was built before their formation and used by Egon, Dr. Stantz, and Dr. Venkman while they were employed by Columbia University.
In the early 1990s, Dr. Spengler experimented with installing digital versions of Tobin’s Spirit Guide that can be crossed referenced with scans straight from the P.K.E. meter. There were also tests to include P.K.E. scanning technology in ecto goggles, but proved to be faulty and inaccurate.
By 2010, P.K.E. meters included wi-fi capabilities and were able to analyze scanned data with Ghostbusters International database on cloud storage and can transmit data to tablets for further analysis.