Abstract: The present invention concerns an improved optical method and optical sensing device for determining the levels of polyhydroxyl-substituted organic molecules in vitro in aqueous or organic media. Specifically, a dye is combined with an conjugated nitrogen-containing aromatic heterocyclic aromatic boronic acid-substituted bis-onium compound in the presence of a sugar, such as fructose or glucose. The viologens are preferred as the aromatic conjugated nitrogen containing boronic acid substituted compounds. The method is useful to determine sugar levels in fermentation and process streams.

Abstract: A photoelectric sensor has its own cleaning system which accommodates different possibilities for mounting the photoelectric sensor, so that it is no longer necessary to custom design cleaning systems. The photoelectric sensor includes an optical lens and a cleaning device which cleans the optical lens. The cleaning device further includes a fluid chamber coupled to a source of fluid, and a fluid dispenser in fluid communication with the fluid chamber and disposed adjacent the optical lens. The fluid dispenser is operative to dispense fluid on the optical lens to clean the optical lens. In a preferred embodiment, the cleaning system uses a pulse of air to remove dust from the optical lens of the photoelectric sensor.