# Soft Rehabilitation and Nursing-Care Robots: A Review and Future Outlook
## 2 Mechanical Design
### Soft Rehabilitation and Nursing-Care Robots Based on the Soft Intelligent Materials Actuation
#### 2.2.2 Other Soft Intelligent Materials
They made a sample of the driving mechanism based on the calculated design parameters. In the same year, [PERSON] et al. developed a dielectric elastomer actuator (DEA) for wrist-assisted wearing device [88]. A dielectric elastomer actuator has a mass of 20.9 g and the parts connected to the base account for most of the weight. 12 DEAs were constructed, and a test was conducted to evaluate their potential as an actuation of wrist rehabilitation devices. According to the experimental results, a single DEA cannot fully drive the assistant wearable device of the wrist and the Muti-DEAs system maybe a possible solution. To the best of our knowledge, there are very few applications of SRNCR based on hydrogel. The author collected some information about hydrogels for researchers who might be interested in this field in the future. In 2015, [PERSON] et al. proposed a spine-like manipulator with a bio-probe--SpineMan [89]. The SpineMan consists of rigid components made of polypropylene and soft components made of polyvinyl alcohol (PVA) borax hydrogel wrapped in the silicone skin. The manipulator follows the unique structure of the mammalian spine and has a high level of flexibility and softness as well as adequate load-bearing capacity. [PERSON] et al. demonstrated a highly flexible hydrogel in [90] and used it to make a soft actuator. Its excellent biological characteristics make it have great potential in the medical field. [PERSON] et al. proposed a hydraulic hydrogel actuators made of polyacrylamide (PAAm)-alginate hydrogels and designed a simple robot based on it [91]. These actuators have a short response time and a large driving force. PAAm-alginate hydrogels has excellent fatigue resistance under moderate stress. The actuator made of it can maintain its robustness and functionality in multiple driving cycles. The above literature shows that hydrogels have extraordinary potential in the field of SRNCRs. The mechanical structure of the SRNCR based on soft intelligent materials mentioned above is summarized as shown in Table 2. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Robots** & **Aims** & **Assistance Capacity/Experimental Result** \\ \hline Soft pneumatic rehabilitation glove except thumb [49] & Designed for hand rehabilitation & 1.21 / 1.09 / 1.21 / 0.91N for PFA/ MFA/ RFA/ SFA (@43 kPa); curling more than 320\({}^{\circ}\) \\ \hline Soft robotic rehabilitation glove [52] & Providing assistance for individuals with functional grasp pathologies & a notable increase in the speed, precision and accuracy of the grasp for Box-and-Block test \\ \hline Soft actuator [54] & Soft actuator for hand rehabilitation robots & About 15\({}^{\circ}\)-150\({}^{\circ}\) bending angle \\ \hline Soft pneumatic finger [53] & Helping patients bend and extend the disable hand in a large range of safety & Soft pneumatic finger can drive index finger to maximum bend angles \\ \hline Power assistive and rehabilitation glove [55] & providing assistive force for griping and pinching movements & Maximum force up to 17N (@4 bar); amplifying patient’s force up to 40\% and 45\% \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Overview of soft rehabilitation and nursing-care robots based on soft intelligent materials. Figure 5: Soft rehabilitation and nursing-care robots based on other soft intelligent materials. (**a**) is reprinted from [81]. (**b**) is reprinted from [84].