When the applied potentials were controlled in the range of 25 e40 V and the humidity of the environment was in the range of 65e80%, clear fingerprints can be obtained by rolling the bare finger on the Prussian film.
When the applied potentials were controlled in the range of 25e40 V and the humidity of the environment was in the range of 65e80%, clear fingerprints can be obtainedby rolling the bare finger on the Prussian film.