Inventories (Details) (USD $)	Dec. 31, 2012	Dec. 31, 2011
Components of inventories
Raw materials	$ 1,685,493	$ 1,514,928
Work in process	2,602,990	1,441,231
Finished goods	1,745,052	1,492,488
Inventory gross	6,033,535	4,448,647
Less: reserve for obsolete inventory	(135,980)	(172,557)
Inventory net	$ 5,897,555	$ 4,276,090