A Microcontroller-Based Device for Liquid Intake and Lick Analysis in Rodents

Drinking behavior is an important parameter in laboratory animal experiments. Traditionally, the amount of fluid consumed is recorded manually by the experimenter, who weighs the bottle at predetermined timepoints to calculate the intake. This approach is labor-intensive and involves human intervention, which can disturb the animals and affect their natural drinking patterns. Automated drinkometer systems have been developed to enable continuous and automated recording of fluid consumption. One advantage of these devices is that they allow researchers not only to measure total fluid intake but also to analyze the microstructure of drinking behavior (e.g., number of licks, bouts, and inter-bout intervals). However, these systems typically require dedicated cages equipped with proprietary drinkometers, making them highly expensive and often unsuitable for monitoring fluid consumption under standard home cage conditions. Here, we describe the development of a new cost-effective microcontroller-based device for continuous monitoring of liquid consumption and analysis of licking microstructure, which can be integrated with existing cages. The system is based on capacitive sensing technology for the assessment of liquid consumption. A customized bottle handler and capacitive sensor have been designed, which can be mounted on a standard 250 mL sized bottle for data acquisition. The device has been tested both in mice and in rats. The results demonstrated that for both animal species the system reproducibly and reliably recorded fluid consumption, also allowing for licking analysis. The data are acquired autonomously through custom devices and directly transferred to a computer for storage and analysis.