# Review of the Research Progress in Soft Robots
## 3 3D Printing Manufacturing Process
### Inkjet Printing (IP)
\begin{table}
\begin{tabular}{c c c c c} \hline
**Classification** & **Materials** & **Advantages** & **Disadvantages** & **Applications** \\ \hline \multirow{4}{*}{SLA} & Photosensitive modified silicone materials & Accurate control of the shape and size of the part & \begin{tabular}{c} \multicolumn{1}{c}{Cannot achieve} \\ multi-material printing \\ \end{tabular} & Octopus like robots [76] \\ \cline{2-5}  & \multirow{2}{*}{Hydrogel materials} & \multirow{2}{*}{Smooth surface} & Materials with generally toxic & Micro soft robot [116] \\ \cline{2-5}  & & & \begin{tabular}{c} Need extra print support \\ and manually remove \\ \end{tabular} & \begin{tabular}{c} Magnetic response \\ octahedron [117] \\ \end{tabular} \\ \cline{2-5}  & & & Curl or break when cured & Flexible sensor [118] \\ \hline \multirow{4}{*}{DLP} & Photopolymer & Fast formation & \begin{tabular}{c} High purity liquid \\ photopolymer \\ \end{tabular} & Software gripper \\ \cline{2-5}  & \multirow{4}{*}{High precision} & & \\ \cline{2-5}  & & High surface finish & & \\ \cline{2-5}  & & Low cost & & \\ \cline{2-5}  & & Safe and reliable & & \\ \hline \multirow{4}{*}{FDM} & TPU, SMP, P2 VP, ABS & Low cost & Long molding time & Soft gripper [119] \\ \cline{2-5}  & \multirow{4}{*}{\begin{tabular}{c} Formal \\ accessibility, compatibility, and usability \\ \end{tabular} } & \begin{tabular}{c} Materials with \\ extrusion nozzle and \\ molding effect \\ \end{tabular} & pH response parts [120] \\ \cline{2-5}  & & \begin{tabular}{c} Small environmental \\ pollution \\ \end{tabular} & \begin{tabular}{c} Need extra print support \\ and manually remove \\ \end{tabular} & \\ \hline \multirow{4}{*}{DIW} & Silicone rubber & Fast printing speed & Low accuracy & Software gripper [121] \\ \cline{2-5}  & Silicone, hydrogel & Low cost & Need extra print support & crawling robot [122] \\ \cline{2-5}  & Liquid metal & Widely used & & Magnetic elastomer [123] \\ \cline{2-5}  & Nano silver & Easy to operate & & \\ \hline \multirow{4}{*}{SLS} & TPU and other & \begin{tabular}{c} Materials with \\ thermoplastic materials \\ \end{tabular} & \begin{tabular}{c} Laser radiation \\ accessibility and usability \\ \end{tabular} & Soft gripper [124] \\ \cline{2-5}  & & High precision & High cost & \\ \cline{2-5}  & & High reducibility & Low efficiency & \\ \cline{2-5}  & & Function test or assembly & Limited by material & \\ \hline \multirow{4}{*}{SDM} & Active agent mixing & High manufacturing & Rough surface & Soft gripper [124] \\ \cline{2-5}  & material & accuracy & High cost & Crawling robot \\ \cline{2-5}  & & & High control requirements & \\ \cline{2-5}  & & & Fatigue failure & \\ \hline \multirow{4}{*}{IP} & Tangoplus materials & \begin{tabular}{c} Simple molding \\ mechanism \\ \end{tabular} & The print head blockage & The print head blockage \\ \cline{2-5}  & Vero white materials & Fast molding speed & Difficult to control the size of the ink droplets & \begin{tabular}{c} Hardness gradient \\ distribution software \\ driver [125] \\ \end{tabular} \\ \cline{2-5}  & No internal stress & \
\begin{tabular}{c} The printing process \\ accompanied by nozzle \\ offset \\ \end{tabular} \\ \cline{2-5}  & No additional support &
\begin{tabular}{c} The printed product with \\ serious grain \\ \end{tabular} \\ \cline{2-5}  & Low cost & & \\ \hline \end{tabular}
\end{table} 
Table 3: Materials, advantages, disadvantages, and applications of different 3D printing manufacturing processes.