Development of Eight Wireless Automated Cages System with Two Lickometers Each for Rodents

Drinking behavior has been used in fundamental research to study metabolism, motivation, decision-making and different aspects of health problems, such as anhedonia and alcohol use disorders. In the majority of studies, liquid intake is measured by weighing the bottles before and after the experiment. This method does not tell much about the drinking microstructure, e.g., licking bouts and periods of preference for each liquid, which could be valuable to understand drinking behavior. To improve data acquisition of drinking microstructure, companies have developed lickometer devices that acquire timestamps when animals approach or drink from a specific sipper. Nevertheless, commercially available devices have elevated costs. Here, we present a low-cost alternative for a lickometer system that allows wireless data acquisition of licks from eight cages with two sippers each. We ran a three-phase validation protocol to ensure (1) proper choice of the sensor to detect licks; (2) adaptation of the device to a wireless transmission and realistic in silico tests; and (3) in vivo validation to test the correlation between the amount of licks measured by the lickometer and the bottle weight. The capacitive sensor presented appropriate recall and precision for our device. After adaptation to wireless transmission, the in silico validation demonstrated low reading and transmission errors even when tested in extreme simultaneous licking conditions. Finally, we observed a positive correlation between water or ethanol consumption and lick count, showing that the lickometers can be used for in vivo studies interested in rodent drinking microstructure.