Fig. 4: Wireless transmission and remote monitoring for intelligent CPM system.

a Circuit scheme showing signal transduction, processing, and wireless transmission from sensing system to mobile terminal. b Relationship between bending angle and arc length during knee rotation. c Photos of patient’s in situ monitoring by passive motion at different angle with the assembled organogel sensors on intelligent CPM machine in Xi’an Honghui Hospital (Scale bar: 50 cm). d Relationships between measured angle and calculated angle of CPM system at different bending angles, respectively. e, f Angle and relative resistance changes of joint movement assembled of intelligent CPM system.