Device, system and method for in-vivo detection of H. pylori. For example, an in-vivo device includes a housing, a reference electrode disposed on the housing, and a working electrode disposed on the housing in close proximity to the reference electrode. The working electrode is coated by litography or screen printing with salt such that substantially no current passes between the working electrode and the reference electrode. The in-vivo device further includes a measuring device for measuring current, impedance, and/or resistance between the working and the reference electrodes, and a transmitter for transmitting the measurements. Presence of ammonia, which is a byproduct of H. pylori, causes increase in current and thus decrease in impedance or resistance between the reference electrode and the working electrode thereby measurements of current, impedance, and/or resistance indicate on presence or absence of H. pylori.
