Multi-Channel data logging simultaneously with different files of sd card.

:confused: hello friends good evening to every one.
i have develop a 4 channel Data logger which have 2 types of inpurt,1st is potentiometric and 2nd is bridge type sensors i/p. All four channel working properly and store there data in sd card with different different file related to there channel individually. I want to run or log all four channels simultaneously or parallel with different or same time interval. how can i do this, any suggestion will be appreciable. thanks in advance. 8)
I am not able to post my code, bcz it have more then 3500 lines. u can understand.

I would store the data in one file, using a channel identifier and time stamp with each measurement. Sort the measurements out later on a PC.

The standard Arduino does not have enough memory to keep several files open at the same time.