Digital pipette: open hardware for liquid transfer in self-driving laboratories

Self-driving laboratories are being investigated as a potential means to accelerate the material discovery process. Accurate liquid handling is an essential operation in the context of chemical laboratories, and consequently a self-driving laboratory will require robotic liquid handling and transfer. Although many pipettes are available for human scientists, robots cannot manipulate these pipettes due to the limitations of current robot gripper morphology. We propose an intuitive yet elegant design for a 3D-printed digital pipette designed for robots to carry out chemical experiments. It costs less than 200 USD, and the simple design with three parts enables a new user to assemble one in 10 minutes. We conducted a performance evaluation that closely followed ISO 8655-6. Our results show that robots with the digital pipette could conduct accurate liquid delivery with 0.2% random error for the nominal volume (10 mL). This performance is comparable to commercially available liquid handling devices, whose typical random errors are 0.3%. We propose an economical 3D-printed pipette, which aims to overcome the limitations of two-finger robot grippers. It enables general-purpose robot arms to achieve high precision in liquid transfer tasks that is comparable to commercial devices.