A pH sensor includes an enclosed fluidic channel, an electrolyte solution within the fluidic channel, a first electrode exterior to the fluidic channel, a second electrode within the fluidic channel, a liquid junction extending between the fluidic channel and an exterior of the fluidic channel. The liquid junction is adapted to provide fluid connection between the electrolyte solution within the fluidic channel and an exterior of the fluidic channel. The pH sensor further includes a fluidic switch or fluidic controller in operative connection with the liquid junction to control whether the liquid junction provides fluid connection between the electrolyte solution within the fluidic channel and the exterior of the fluidic channel.
