Transcranial electrical stimulation (tCES) is a non-invasive and safe treatment, which uses a low direct current or alternating current to change the excitability of the cerebral cortex. The tCES has been applied in clinical trials related to rehabilitation research in recent years, and the safety and effectiveness have also been established. However, the existing tCES products effect on the whole brain networks and lack special waveforms. We developed a wearable high-definition tCES (HD-tCES) with special waveforms. This novel stimulation system will result in more precise and focal stimulation of selected brain regions with special waveforms to display better neuromodulation performance. In this study, we will preliminarily examine the effects and safety of the HD-tCES on lower extremity in patients with stroke. We expect that the HD-tCES combined with the lower extremity rehabilitation can shorten the duration of rehabilitative periods, improve stroke patients' activity of daily living, reduce the care burden of patients' family, and subsequently decrease the cost of health care insurance.

Inclusion Criteria:

1. With a diagnosis of stroke.
2. Age ≥ 20 years.
3. Hemiplegia, Brunnstrom stage III-V.
4. 6 months to 5 years after stroke.
5. Muscular inelasticity (spasticity) 1-3 on the affected lower limb, evaluated by the Modified Ashworth Scale.
6. Ability to walk for 10 min non-stop with no gait aids or ability to walk 20 m with supervision or slight assistance.

Exclusion Criteria:

1. Intolerance to electrical stimulation.
2. Contracture on lower extremities, and limitation in joint range of motion.
3. Severe spasticity.
4. Ossification or inflammation in muscle tissue.
5. A history of arrhythmia.
6. Implantable medical electronic devices (e.g., like pacemaker).
7. Metal implants in the head or neck.
8. Wounds on the skin of head.
9. A history of brain surgery or severe brain trauma.
10. Severe cognitive or psychiatric disorders (e.g., schizophrenia, depression or bipolar disorder).
11. A history of seizure or other brain pathology.
12. Drug or alcohol abuse.
13. Malignant neoplasm or rheumatism disorder (e.g., SLE, RA, AS, IBD)
14. Undergoing other non-invasive brain stimulation.
15. Intra-cerebral lesions (such as brain tumors, arteriovenous tumors).
16. History of encephalitis or meningitis.
17. Stroke lesion in cerebellum or brainstem.
18. Leg amputation.
19. Sleep deprivation.
20. Severe or recent heart disease.
21. Subjects who use drugs that may lower the seizure threshold.
22. Pregnant or breastfeeding women.