Supplementary Balance Sheet Information - Accrued Expenses (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued compensation	$ 1,003,383	$ 780,848
Preferred stock dividend	365,255	341,015
Research agreements and clinical trials	1,686,068	319,898
Director fees	67,500	80,008
Professional fees and outside services	21,000	107,006
Patent, license and other fees	69,950	58,398
Other accrued liabilities	46,905	84,669
Total accrued liabilities	$ 3,260,061	$ 1,771,842