# A Smart Rehabilitation Glove Based on Shape-Memory Alloys for Stroke Recovery
## 3 Method  
### SMA Materials and Methods  
To perform rehabilitation exercises for patients with different conditions, the diameter and length of SMA wires were selected to provide sufficient driving force and contraction length for training. The basic movements of rehabilitation training involve the bending and straightening of the finger joints. The minimum motion requirement for patients in the early stage of rehabilitation is the achievement of a finger joint circumference C value of 68 mm. We selected a Ni\({}_{50.3}\)Ti\({}_{49.7}\) SMA wire with a diameter of 0.15 mm, which was commercially obtained from PeierTech, Jiangyin, China. The mechanical characteristics of the SMA wires approached a steady state after thermomechanical pretraining. The prestress was 500 MPa during pretraining, and 60 cycles of Joule heating at 40 mA was performed,  
Figure 2: Online functions in mobile application for patients (**a**) and doctors (**b**), respectively.  
which induced saturated dislocations in the NiTi wires to suppress the accumulation of defects in the subsequent cyclic loading fatigue process, and limited the generation of the R phase. The pretraining process helped to stabilize the performance and improved both functional and structural fatigue [34].  
The mechanical properties of both the SMA wires and the fabricated prototype were systematically characterized. Uniaxial tensile tests were performed by dynamic mechanical analysis (DMA 850, TA Instruments, New Castle, DE, USA) with a temperature control box. All DMA tests were conducted under uniaxial tension at constant strain rates, without frequency sweep. The sample was loaded at a strain rate of \(2.5\times 10^{-3}\) s\({}^{-1}\). Some samples were strained to failure, whereas others were strained to 3%, 5%, and 7% strain.  
The thermomechanical tests were conducted at constant temperatures at \(-15\)\({}^{\circ}\)C, \(15\)\({}^{\circ}\)C, \(45\)\({}^{\circ}\)C, and \(75\)\({}^{\circ}\)C, with a controlled strain of 5% and a strain rate of \(5\times 10^{-4}\) s\({}^{-1}\), to obtain the corresponding stress-strain curves.  
Strain-temperature curves were obtained by applying constant tensile stresses (150 MPa, 200 MPa, 300 MPa) with a cooling/heating rate of \(5\)\({}^{\circ}\)C/min.  
The phase-transformation temperatures were determined by differential scanning calorimetry (DSC 8500, PerkinElmer, Waltham, MA, USA) measurements. The temperature range was \(-100\)\({}^{\circ}\)C to \(100\)\({}^{\circ}\)C, with a cooling/heating rate of \(10\)\({}^{\circ}\)C/min, and 3 min isothermal holding at both \(100\)\({}^{\circ}\)C and \(-100\)\({}^{\circ}\)C to ensure complete phase transformation.  
The SMA wire was powered by a laboratory power supply, which generated Joule heating to increase the temperature of the SMA wire to its phase-transformation temperature. This setup was employed to investigate the relationship between the strain of the SMA wire and the magnitude of the applied current, thereby obtaining the current-strain characteristic curve.  
In the experiment comparing contraction forces under different applied voltages, an SMA wire with a length of 15 cm and a diameter of 0.15 mm was secured at one end to a spring dynamometer, while the other end was attached to a weight to ensure the wire remained taut. The wire was subjected to different voltage inputs, and the variations in the dynamometer readings during the electrification process were recorded. Similarly, in the experiment investigating the influence of the length of the wire during electrification, a constant voltage of 4 V was applied and the variations in the readings of the spring dynamometer during the process were measured and recorded.