how do I we get to know which all the check box's are TICKED

Question

I have Datagrid in asp.net page with the below mentioned data 

Device Name	Column 1	Column 2
iPad	Check Box	Check Box
iPhone	Check Box	Check Box
iStore	Check Box	Check Box

Here Device_Name,Column1 and Column2 are column names, under these columns we have check boxes on both the columns, Please can anybody help me how do I we get to know which all the check box's are TICKED.


Once it has been TICKED I want to assign checked value (just to identify which are been ticked) to array list from Grid view (for storing purpose, later I will pass this array list to next page). 
find the attched my Code to generate dynamic check boxes in grid view
 

Could you please someone help me one this