Subject: the average dimensions of a mammalian cell: neurons and muscle cells?

We're trying to design a sensor to read the action potential of a certain cell 
line. The cell fits into a well, and the bottom of the well is part of the 
sensor.  The cells will grow in the well, so we have to have a big enough well 
that it doesn't crowd the cell, but the well can't be too big either.
We haven't chosen the cell line yet, but we know that we either have to use 
neurons, muscle cells or cardio cells.  So we're trying to come up with a basic 
design initially, and we need to determine the size of the well that the cell 
is going to fit in.  So we need in-the-ball-park dimensions first.  

Re: the average dimensions of a mammalian cell: neurons and muscle cells?