Inventories (Details) (USD $)	Jun. 30, 2013	Dec. 31, 2012
Components of inventories
Raw materials	$ 1,767,001	$ 1,685,493
Work in process	2,313,621	2,602,990
Finished goods	1,554,424	1,745,052
Inventory gross	5,635,046	6,033,535
Less: reserve for obsolete inventory	(138,791)	(135,980)
Inventory net	$ 5,496,255	$ 5,897,555