Here is the design of a clinical trial:

Official Title: Recovering Arm Function in Chronic Post-stroke Patients Using Combined HD-tDCS and Virtual Reality Therapy

Included conditions:
- Chronic Post Stroke Individuals

Study Armgroups:
- {'label': 'HD-tDCS and Virtual Reality Therapy', 'type': 'ACTIVE_COMPARATOR', 'description': 'Patients will receive their usual rehabilitation program each day, which includes a conventional session (30min) and virtual reality therapy session (Armeo Spring) combined with real stimulation (30min) over 13 consecutive training days (3 weeks)', 'interventionNames': ['Device: HD-tDCS']}
- {'label': 'Sham stimulation and Virtual Reality Therapy', 'type': 'SHAM_COMPARATOR', 'description': 'Patients will receive their usual rehabilitation program each day, which includes a conventional session (30min) and virtual reality therapy session (Armeo Spring) combined with Sham stimulation (30min) over 13 consecutive training days (3 weeks)', 'interventionNames': ['Device: Sham HD-tDCS']}

Interventions:
- {'type': 'DEVICE', 'name': 'HD-tDCS', 'description': 'Real stimulation (2mA, 20min) with anode on C3/C4 of the lesioned hemisphere and 4 return electrodes \\~4cm away', 'armGroupLabels': ['HD-tDCS and Virtual Reality Therapy'], 'otherNames': ['Starstim8 (Neuroelectrics, Spain)']}
- {'type': 'DEVICE', 'name': 'Sham HD-tDCS', 'description': 'Sham stimulation (2mA, ramp up and down phases of 30s) with anode on C3/C4 of the lesioned hemisphere and 4 return electrodes \\~4cm away', 'armGroupLabels': ['Sham stimulation and Virtual Reality Therapy'], 'otherNames': ['Starstim8 (Neuroelectrics, Spain)']}

Primary Outcomes:
- {'measure': 'Change in Functional Motor capacity of the upper extremity', 'description': 'Arm functional capacity assessed by the Wolf Motor Function Test (WMFT) (0-75, where higher scores mean better arm functional capacity)', 'timeFrame': 'Change from Baseline at Day 21(after intervention) and 3 months after day 21'}
- {'measure': 'Change in Functional Motor capacity of the upper extremity', 'description': 'Arm functional capacity assessed by the Wolf Motor Function Test (WMFT) (0-75, where higher scores mean better arm functional capacity)', 'timeFrame': 'Change from Day 21 at 3 months (retention)'}
- {'measure': 'Change in Motor deficit of the upper extremity', 'description': 'Measured by the Fugl-Meyer Upper Extremity (FMUE) score (0-66, where higher scores mean a better recovery)', 'timeFrame': 'Change from Baseline at Day 21 (after intervention) and 3 months after day 21'}
- {'measure': 'Change in Motor deficit of the upper extremity', 'description': 'Measured by the Fugl-Meyer Upper Extremity (FMUE) score (0-66, where higher scores mean a better recovery)', 'timeFrame': 'Change from Day 21 at 3 months (retention)'}
- {'measure': 'Change in Hand dexterity', 'description': 'Measured by the Box and Block Test (BBT) score (greater number of blocks moved in 1minute means better hand dexterity)', 'timeFrame': 'Change in Baseline at Day 21 (after intervention) and 3 months after day 21'}
- {'measure': 'Change in Hand dexterity', 'description': 'Measured by the Box and Block Test (BBT) score (greater number of blocks moved in 1minute means better hand dexterity)', 'timeFrame': 'Change in Day21 at 3 months (retention)'}

Please estimate the sample size based on the assumption: 
An alpha bilateral risk of 5%, a power of 80%, and a 10% loss of patients are assumed.
Sample size
          Allman et al. [1] reported that compared to sham, real anodal tDCS (1 mA, conventional montage, ipsilesional motor cortex) combined with 9 days of UL rehabilitation in chronic stroke patients had a moderate effect size d = 0.4 on the WMFT at 3 months after the intervention. In the meta-analysis of Chhatbar et al. [16], UL motor recovery (FM-UE) in a chronic stroke population was superior in the group receiving a real tDCS (in comparison to sham) with higher current density and smaller electrode size (large effect size g = 1.23). Because we will use anodal HD-tDCS with a higher current density (2 mA) and longer rehabilitation dose (13 days) in chronic stroke patients, we estimate that our protocol should have an effect size of d = 0.8 on the WMFT at 3 months. Using an alpha bilateral risk of 5% and a power of 80%, 26 patients per group are needed for analysis. If we count a loss of 10% of the patients, we will have to recruit 58 patients (n = 29 per group).