"Because “[c]onception is the touchstone of inventorship,” each joint inventor must generally contribute to the conception of the invention. Burroughs Wellcome Co. v. Barr Labs., Inc., 40 F.3d 1223, 1227-28 (Fed. Cir. 1994). Additionally, courts require corroborating evidence of conception. Id. at 1228. However, contribution to one claim is sufficient to be a co-inventor. Ethicon, Inc. v. U.S. Surgical Corp., 135 F.3d 1456, 1460 (Fed. Cir. 1998). Conception is defined as “the ‘formation in the mind of the inventor, of a definite and permanent idea of the complete and operative invention, as it is hereafter to be applied in practice.’” Hybritech Inc. v. Monoclonal Antibodies, Inc., 802 F.2d 1367, 1376 (Fed. Cir. 1986) (citation omitted). Conception is complete when “the idea is so clearly defined in the inventor’s mind that only ordinary skill would be necessary to reduce the invention to practice, without extensive research or experimentation.” Burroughs Wellcome, 40 F.3d at 1228."

(Fredric A Stern v. Columbia University and Lazlo Z Bito)