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International Journal of Bioprinting Automated bioink mixer improves bioprinting

Figure 2. Design of the bioink mixing device and hydrogel mixing at different conditions. (A) The user determines the input parameters through the
human–machine interface (HMI), which is connected to a microcontroller unit (MCU) that transmits the settings to the stepper motor. The motor finally
drives the sliding table and thereby mediates mixing of the bioink. (B) A picture of the automated bioink mixing device. (C) Schematic of the working
principle of the automated mixing device and hydrogel mixing in connected syringes.

The components were optimized and assembled prior to China) in deionized water with magnetic stirring at 37°C
program design, structural modeling, motion validation, overnight. To mimic the cell suspension and determine
and stability test. Parameters such as mixing speed, number the blending state, an aqueous solution with 0.001% (w/v)
of exchanges, and delay time can be set directly via the methylene blue (M9140, Sigma, Munich, Germany) was
control unit on the mixing machine. These settings regulate used. For hydrogel mixing, the alginate solution and the
the stepper motor, thereby controlling the movement of methylene blue solution were loaded into separate syringes,
the sliding table. For hydrogel mixing, the loaded syringes which were then coupled and subjected to mixing process
(Omnifix Luer-Lock Solo 3 mL, B. Braun Melsungen AG, on the developed automated mixing device. Throughout
Melsungen, Germany) were introduced into the mixing the process, the mixing effect was observed and recorded
unit, and the mixing process was carried out according to using a digital camera (EOS 700D, Canon, Tokyo, Japan).
the settings. The photos were subsequently evaluated by examining the
distribution of the blue color and scored from 0 to 10 points.
2.2. Preliminary hydrogel mixing test
Sodium alginate solutions of varying concentrations (2%, 2.3. Cell culture
4%, 6%, 8%, 10% (w/v)) were prepared by dissolving HEK293-GFP cells (human embryonic kidney cells that
sodium alginate powder (W201502-1KG, Sigma, Shanghai, express green fluorescence protein [GFP]) were purchased

Volume 10 Issue 2 (2024) 383 doi: 10.36922/ijb.1974