Participants are seeking to unleash the full therapeutic potential of a newly developed, customizable and potentially commericializable 10-channel Functional Electrical Stimulation (FES) to rehabilitate the gait of chronic stroke survivors. Patricipants will utilize the theory of muscle synergies from motor neurosciences, which are defined as neural modules of motor control that coordinate the spatiotemporal activation patterns of multiple muscles, to guide our personal selections of muscles for FES. Before applying FES stimulations to chronic stroke survivors, participants will have to define normal muscle synergies from age-matched healthy control participants (1 session for each participant). After comparing the difference in muscle synergies in both healthy subjects and chronic stroke survivors, participants are attempting to rehabilitate the gait of chronic stroke survivors by using the wearable. Each chronic stroke survivor will undergo 18-session FES training (\ 1 month). It is hypothesized that FES will promote motor recovery by supplying the missing normal muscle synergies to chronic stroke survivors at their supposed times of activations in each step cycle during interventional training. It is also expected that the walk synergies of the paretic side of chronic stroke survivors should be more similar to healthy muscle synergies at the two post-training time points than before training. The healthy normal muscle synergies will be defined by EMG recordings from the recruited healthy participants.