Abstract: A novel method for forming a gel matrix. In this method an apparatus is provided which includes a first and second plate, each plate having a flat surface, and a spacer. The spacer is positioned between the flat surfaces of the two plates so that the flat surfaces are located close to each other with a gap from the top of the plates to the bottom of the plates. The apparatus is placed into a generally rectangular liquid impermeable bag having one top open end, a bottom end and a side wall therebetween. The apparatus is placed into this bag such that the top of the plates is parallel to the top open edge of the bag, and the bottom of the plates is located adjacent the bottom end of the bag. The apparatus is fixed, e.g., clamped, in place firmly within the bag and a gelling solution poured into the gap between the plates. This gelling solution is then allowed to set to form the desired gel matrix.