2D Clinostat for Simulated Microgravity Experiments

Ground-based microgravity simulators, such as rotating 2D clinostats, are valuable tools for studying gravity-related processes. This work presents a versatile, g-value-adjustable 2D clinostat designed to hold a single 90 mm Petri dish.

The drive unit is an SM-28BYJ-48-5V stepper motor coupled to an external 12/44 gear set. The 28BYJ-48 is a 5-wire, 4-phase unipolar stepper motor operating at 5 V. It includes an internal gearbox with a 64:1 reduction ratio. Stepper motors are controlled by electrical input pulses, so the rotational speed is proportional to the pulse rate. In full-step mode, this motor rotates 11.25° per step (or 5.625° in half-step mode). The minimum step angle is therefore 5.625°/64. With the two external gears, one full rotation of the wheel corresponds to approximately 7,500 steps. Consequently, the rotating wheel can operate at a speed of 0–10 rpm.

The motor is controlled by an Arduino via a ULN2003 driver module. The ULN2003 module is bolted to the back of the t