Inclusion Criteria:

1. Age ≥22 years and <80 years, all gender is acceptable.
2. History of unilateral supratentorial ischemic stroke ≥ 9 months but < 10 years.
3. Upper Extremity motor section of the Fugl-Meyer Assessment score ≥20 and ≤50.
4. Right- or left-sided weakness of upper extremity.
5. Ability to communicate, understand, and give appropriate consent. Subjects can follow trial commands.
6. Subjects have good compliance and can complete the visits after surgery.

Exclusion Criteria:

1. History of hemorrhagic stroke.
2. Presence of ongoing dysphagia or aspiration difficulties.
3. Prior injury to vagus nerve, either bilateral or unilateral.
4. Subject receiving medication that may significantly interfere with actions of VNS on neurotransmitter systems at study entry, clinic rehabilitation follow-up timepoint, or home rehabilitation follow-up timepoint, such as centrally acting cholinoceptor blockers, centrally acting adrenoceptor blockers, norepinephrine re-uptake inhibitors, etc.
5. Botox injections within 4 weeks prior to enrollment through the unmasking follow-up timepoint (Visit 6).
6. Severe spasticity of the upper extremity (Modified Ashworth ≥ 3).
7. Significant sensory loss of the upper extremity (Upper Extremity sensory section of the Fugl-Meyer Assessment score < 6).
8. Severe depression (Beck Depression Scale > 29).
9. Current requirement, or likely future requirement, of diathermy.
10. Current use of any other stimulation device, such as a pacemaker or other neurostimulator.
11. Pregnancy or plans to become pregnant or to breastfeed during the study period.
12. Participated in any other clinical trials within the preceding 3 months.
13. Not considered to be applicable by the investigator.