I found that bacteriorhodopsin emulsion recipe. Why solgel step is used , cant we use only 221 or something for 222 ? Its possible to record 5000 lp/mm with these emulsions. Bacteriorhodopsin (bR), polyvinyl alcohol (PVA), HCl, sodium borate, boric acid and gelatin (GE) were provided from Sigma.Triethanolamine (TEA) and tetraethoxysilane (TEOS) were provided from Fluka. The Glassy surface was provided from Sinagen. 2.2. Preparation of bR films 2.2.1. Preparation of gelatin-polyvinil alcohol matrix Bacteriorhodopsin films in polymer matrices were prepared by using the standard procedures [7,8]. One mg of bR was soaked in 1ml tri-distilled water for 20 min. Following, 0.4 M of triethanolamine (TEA) aqueous solution was added to the bR suspension to give a TEA:bR molar ratio of 250:1 (which give maximal photosensitivity). 0.0005 gr of PVA and 0.0005gr of GE powders were solved in 100ml tri-distilled water for 20 minutes to prepare PVA and GE solutions. The resulting solution was heated and stirred at 60 °C for 40 min. Finally, the appropriate ratio of bR-TEA and GE-PVA solutions were mixed and stirred for 2030 minutes to make a film-forming solution . 2.2.2. Preparation of sol-gel matrix Tetraethoxysilane (TEOS) were used as precursors for the sol-gel glass. TEOS (7 ml), 3.0 ml of distilled water and 0.1 ml of 0.04 M HC1 were mixed together and sonicated for 20 min. The resulting product was diluted with an equal volume of distilled water. The resulting mixture (0.5 ml) was mixed with 0.25 ml sodium borate buffer solution (pH 9) and (0.1 ml, 0.2 ml) bR solution to create a film-forming solution. Triethanolamine (TEA) was chosen as sensitizing additives. The concentration of chemical additives was in the range of 0.010.4 M. For the preparation of chemically modified films, bR solution was mixed with TEA, before mixing with the sol mixture, and afterwards 0.02 ml of the bR-chemical additives mixture was added to 0.12 ml of the sol mixture [7,8].