Form Validation for Chinese Words

I am using library of Form Validation in CodeIgniter.

Below config try to include all Number, English words, Chinese words and space. But it's not work.

Code:

$config = array(
               array(
                      'field' => 'keywords',
                      'label' => 'keywords',
                      'rules' => 'regex_match[/[a-zA-Z0-9 \u4e00-\u9fa5]+$/]'
                   )
               );

However, if I deduce '\u4e00-\u9fa5', it's work for English words.

Code:

$config = array(
                   array(
                          'field' => 'keywords',
                          'label' => 'keywords',
                          'rules' => 'regex_match[/[a-zA-Z0-9 ]+$/]'
                       )
                   );

Somebody tell me that 'uxxxx' is not work in PCRE.  They suggest me that "/\A[a-zA-Z0-9\s\p{Han}]+\z/".

I test "/\A[a-zA-Z0-9\s\p{Han}]+\z/" in online test website https://regex101.com/r/bC2iK2/1.  It's work. 
However, it is not work in my website.

Code:

$config = array(
                   array(
                          'field' => 'keywords',
                          'label' => 'keywords',
                          'rules' => 'regex_match[/\A[a-zA-Z0-9\s\p{Han}]+\z/]'
                       )
                   );