Figure 3.

Extracellular amplifier and data flow. (A) Photograph of the custom two-channel extracellular amplifier. The design contains two head stages to convert the impedance. They are located close to the bee's head. Each analog signal is then processed separately by amplifiers (amplification factor: 1,000x) and active filters (bandpass: 300 Hz–10 kHz). The resulting analog signals were then digitized by two synchronized delta-sigma analog to digital converters (16 bit, 20 kHz sampling frequency). Two galvanic isolators isolated the digital signals to not pick up any noise from the data storing microcontroller (STM32F4). (B) Schematics of the system with a STM32F4 as on-board computer. Diagram of all electrical components of the neurocopter system and the used buses additionally to the components which are parts of the DJI Matrice 100 quadcopter. The blue arrows represent data transfer. The direction of an arrow symbolizes the direction of the information flow. The red arrows show power supplies and their respective voltages. To make the code hardware independent, the STM32 cube hardware abstraction layer was used for hardware access.