diff --git a/pipelines/data_integration.py b/pipelines/data_integration.py
index aaf49a4..46a7e36 100644
--- a/pipelines/data_integration.py
+++ b/pipelines/data_integration.py
@@ -1,5 +1,6 @@
 import sys
 import os
+import re
 
 try:
     thisFilePath = os.path.abspath(__file__)
@@ -66,6 +67,28 @@ def load_config_and_setup_logging(yaml_config_file_path, log_dir):
     missing_keys = [key for key in required_keys if key not in config_dict]
     if missing_keys:
         raise KeyError(f"Missing required keys in YAML configuration: {missing_keys}")
+    
+    # Check the instrument_datafolder required type and ensure the list is of at least length one.    
+    if isinstance(config_dict['instrument_datafolder'], list) and not len(config_dict['instrument_datafolder'])>=1:
+        raise ValueError('Invalid value for key "instrument_datafolder". Expected a list of strings with at least one item.'
+                         'Each item represents a subfolder name in the input file directory, where the name'
+                         'must match the format "<subfolder>[/<subfolder>]".'
+                         'The first subfolder name is required, and the second is optional. '
+                         'Examples of valid values: "level1", "level1/level2".')
+    
+    # Define the pattern for valid subfolder names: `subfolder` or `subfolder/subfolder`
+    #valid_pattern = re.compile(r'^[^/]+(/[^/]+)?$')
+
+    # Validate each subfolder name
+    #for folder in config_dict['instrument_folder']:
+    #    if not isinstance(folder, str) or not valid_pattern.match(folder):
+    #        raise ValueError(
+    #            'Invalid value for key "instrument_folder" in YAML file.'
+    #            'Each item must be a string matching the format '
+    #            '"<subfolder>[/<subfolder>]". The first subfolder name is required, and the second is optional. '
+    #            'Examples of valid values: "level1", "level1/level2". '
+    #            f'Invalid item: {folder}'
+    #        )
 
     # Validate integration_mode
     integration_mode = config_dict.get('integration_mode', 'N/A')  # Default to 'collection'