signalname = {'Torque';'Torque1'};
This will give you a column vector of cells. Each of the cells will contain a row vector of characters (that is, a string.) You would access the content with signalname{i} instead of signalname(i)
Another possibility is
signalname = char({'Torque';'Torque1'});
This will give you a 2 x 7 char array in which you accessed signalname(i,:) to get the content. Each row in which the original content was shorter than the longest line will be blank padded, so you may wish to use strtrim(). Note that this does not satisfy your requirement that a vector be used.
