Table 1.

Preparation of bi-layered hydrogels (BH) with varying expansion ratio of second layer.

Sample	First Layer				Second Layer
	Aam a	MBA b	Irgacure 2595 c	Expansion Ratio d	Aam a	MBA b	Irgacure 2595 c	Expansion Ratio d
BH-1	20	0.04	0.2	0.681	20	0.30	0.2	0.569
BH-2	20	0.04	0.2	0.681	20	0.20	0.2	0.536
BH-3	20	0.04	0.2	0.681	20	0.10	0.2	0.406
BH-4	20	0.04	0.2	0.681	20	0.08	0.2	0.385
BH-5	20	0.04	0.2	0.406	20	0.04	0.2	0.681

^a Concentration of monomer %(w/v), ^b Concentration of cross-linker %(w/v), ^c Concentration of photo-initiator %(w/v), ^d Expansion ratio of each layer.