“…However, the maximum attainable temporal resolution in the present imaging techniques for skin tissue visualization is about 1.5–2 ms [ 47 ], which is not adequate for the real-time visualization of a fluid injected by an NFJIS into the skin tissue matrix. Hence, in majority of the studies, in vitro media like agarose, gelatin, or polyacrylamide gels [ 6 , 7 , 13 , 21 , 36 , 38 , 41 , 43 , 45 , 46 , 48 – 55 ] were used for investigating the dynamic injection characteristics of an NFJIS, while the ex vivo studies were performed via dissection after the injection [ 10 , 11 , 15 , 37 , 38 , 56 – 59 ] or by micro-computed tomography [ 9 ] or X-ray [ 38 , 60 ] imaging techniques. In vitro models are indispensable tools in drug delivery applications for investigating the effect of individual parameters and to tune the independent and alternative parameters.…”