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International Journal of Bioprinting                                 Fluid mechanics of extrusion bioprinting


















































            Figure 3. Schematic of cell deformation during the bioink flow through a chamfered nozzle and distribution of stresses. Adapted with permission from
              63
            ref.  Copyright © 2018 American Chemical Society.

                                                     eq
                                          b e)]}exp (–a pW p ) (X)
             D t = D max – {D max – D e,max[1–exp (–a eτ e               Aexp  − (  k A)                       if 0 < A <  A
                                                                        
                                                                   A =         A (  1                                    0
                                                                                                  k AA− ))
                                                                     eq
                                                                                          
                                                                                             exp
                                                                         A eq 0 ,  +  eq ∞,  −  A ) 1 − ( − (  0     if A  > A 0
                                                                                           
                                                                                                   2
                                                                        
                                                                                       eq 0 ,
               Chirianni et al.  defined W  as a generalized form of                                     (XII)
                                     eq
                           74
                                     p            Aexp  − (  k A)                       if 0 < A <  A
                                                 
            pressure work :                 A =         A (  1                                    0
                       74
                                                                           k AA− ))
                                                                   
                                              eq
                                                                      exp
                                                  A eq 0,  +  eq ∞,  −  A ) 1 − ( − (  0     if A  > A 0
                                                                    
                                                 
                                                                            2
                                                                eq 0,
                          W =  1  ∆ P AL               (XI)       which identifies a portion of the nozzle cross-
                            eq
                                     eq
                                   n
                            p
                               2
                                                               section area that  is  affected  by  cell  distribution.  Here,
               where A  is the equivalent nozzle cross-section area.   A  > 0, A e  q, ∞  > 0, k  ≥ 0, and k  ≥ 0 are model parameters,
                                                                                       2
                                                                              1
                                                                0
                     eq
            Chirianni et  al.  described the different behavior of   and  A e  q,  0   =  A exp (–k A ).  Figure  4A demonstrates
                                                                                    2
                                                                                      0
                                                                            0
                         74
                                                               how these parameters affect  A , allowing for various
                                                                                         eq
            cell damage in Scenarios 1 and 2 based on uneven cell   relationships  between  nozzle  cross-section  and  its
                                                               equivalent area  A  to reproduce a variety of outcomes
            distribution in the nozzle cross-section. They defined           eq
                                                               from previous experimental tests on cell damage during
                                                                                             74
            equivalent area A  as 74                           extrusion bioprinting. Chirianni et al.  validated their cell
                          eq
            Volume 10 Issue 6 (2024)                       121                                doi: 10.36922/ijb.3973
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