MATLAB: Finding a character and returning that character

cell arraycharacterfunction

I have a function:
function [ vowels ] = findVowels( charCell )
%FINDVOWELS
%   charCell: a two-dimensional cell array and each cell contains a
%   character array
%   vowels: a cell array with the same dimensions as charCell that contains
%   only the vowels of each entry, in lower case
vowels=charCell;
switch vowels
  case strfind(charCell, 'a')
      disp('a')
  case strfind(charCell, 'e')
      disp('e')
  case strfind(charCell, 'i')
      disp('i')
  case strfind(charCell, 'o')
      disp('o')
  case strfind(charCell, 'u')
      disp('u')
end
end
And I want the function to search for the vowels and RETURN those vowels for example:
>>X={'hi','hello';'goodbye', 'later'};
>>findVowels(X)
ans=
2x2 cell array
'i'          'eo'
'ooe'        'ae'
My current function results in an error because vowels is not a scalar or a character. How do I go about this to produce a character?
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