Page 379 - IJB-10-3

International Journal of Bioprinting Multi-physical field control inkjet bioprinting

Figure 6. Controlling and optimization of the temperature field for the full process. (A) The temperature control system of MFCPIB. Enlarged image
shows the internal structure of the temperature-controlled printhead. (B) Simulation of the temperature-controlled chamber. (C) Infrared thermography
of the system. (D) Fitted curve of the top cover temperature and air temperature. The correctness of the simulation was verified by comparing two
curves. The functional relationship between the temperatures of the upper cover and the air was obtained. (E) Rheological properties of GelMA. (F)
Infrared thermography of microdroplet temperature. The red triangle represents the maximum temperature of 14.7°C in the chamber, representing
the microdroplet temperature. The correctness of the microdroplet temperature calculation was verified. (G) Diagram of the relationship between air
temperature and microdroplet temperature. The microdroplet temperature was proportional to the air temperature. (H) Observation of microdroplet
formation. (I) Summary of the MFCPIB relationship. To accurately control the final microdroplet molding temperature at 16°C, the corresponding air
temperature to achieve good microdroplet molding was found for different microdroplet diameters and velocities.

and at this point, GelMA began to form a gel and the MFCPIB method, the final assembly temperature of the
viscosity began to increase slowly. The microdroplets microdroplet was controlled near the gel point of 16°C and
in this range are at a critical point of a sudden change in in part II.
viscosity, making GelMA printable. We used the MFCPIB In order to calculate the temperature of microdroplets,
method to control the assembled microdroplets within this we utilized the lumped parameter method. This method is
temperature range. In part III, when the temperature was a simplified analysis technique that disregards the thermal
below 15°C, the storage modulus was much higher than the conductivity resistance of an object. It is applicable when
loss modulus and gradually leveled off. GelMA gradually the heat transfer resistance on the object’s surface is much
completely gelled and the viscosity of GelMA rapidly greater than the thermal conductivity inside the object.
increased in this part. The rheological properties shown Under these conditions, the temperature will remain
in Figure 6E provided a theoretical basis for subsequent constant, assuming the object is at the same temperature
accurate temperature control of microdroplets. Using the at a given moment. To determine the suitability of the

Volume 10 Issue 3 (2024) 371 doi: 10.36922/ijb.2120