Here is the design of a clinical trial:

Official Title: Feasibility of Cognitive Training in Combination With Transcranial Direct Current Stimulation in a Home-based Context

Included conditions:
- Aging

Study Armgroups:
- {'label': 'stimulation group', 'type': 'EXPERIMENTAL', 'description': 'Anodal tDCS+ intensive cognitive Training', 'interventionNames': ['Device: Anodal tDCS', 'Behavioral: Intensive cognitive training']}
- {'label': 'sham group', 'type': 'SHAM_COMPARATOR', 'description': 'Sham tDCS + intensive cognitive Training', 'interventionNames': ['Behavioral: Intensive cognitive training', 'Device: Sham tDCS']}

Interventions:
- {'type': 'DEVICE', 'name': 'Anodal tDCS', 'description': 'Anodal transcranial direct current stimulation (tDCS), 6 sessions with 20 minutes stimulation each (1,5 mA).', 'armGroupLabels': ['stimulation group']}
- {'type': 'BEHAVIORAL', 'name': 'Intensive cognitive training', 'description': 'Intensive cognitive training of a letter memory updating task, 6 sessions for approximately 20 min', 'armGroupLabels': ['sham group', 'stimulation group']}
- {'type': 'DEVICE', 'name': 'Sham tDCS', 'description': 'Sham transcranial direct current stimulation (tDCS), 6 sessions with 30 sec stimulation each (1,5 mA) to ensure blinding of participants.', 'armGroupLabels': ['sham group']}

Primary Outcomes:
- {'measure': 'Feasibility of conducting the intervention in a home-based context', 'description': 'Feasibility of home-based tDCS as operationalized by at least 2/3 (out of 6 planned sessions) successfully performed interventional sessions per participant. A session is regarded as successful if it is marked as completed in the stimulation system.', 'timeFrame': '2 weeks'}

Please estimate the sample size based on the assumption: 
The study uses an independent t-test with a two-sided significance level of 0.05 and a power of 80%. The lower bound of the 95% CI for the proportion of participants meeting the feasibility criterion needs to be at 60%.
Sample size
          As the primary goal of this study will be to assess feasibility, and as it is recommended to employ results of feasibility trials for sample size calculation of a planned subsequent trial,46 we chose a sample size of n=30.47 To infer feasibility, the lower bound of the 95% CI of the proportion of participants who fulfilled the feasibility criterion needs to be at 60%. Thus, 76%, that is, n=23 participants will have to meet the feasibility criterion.
          With 15 participants per stimulation group (anodal vs sham stimulation), we will be able to able to scope the general feasibility of this home-based intervention, and will be able to plan follow-up trails accordingly. Additionally, we will be able to explore descriptively the benefit of anodal tDCS over sham with regard to performance after the training on the trained and untrained working memory tasks to obtain estimates of effect sizes for power calculations of future RCTs.48 49 Using an independent t-test with a two-sided significance level of 0.05 and a power of 80%, we will be able to demonstrate an effect of Cohenâs d=1.06âor higher on behavioural performance.