Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2021

Equity [Abstract]

Common Stock Reserved For Future Issuances

The Company had reserved shares of common stock for future issuance as follows:

	December 31,
	2021		2020
Outstanding stock options		1,542,126		830,343
Outstanding restricted stock units		133,834		29,087
Warrants to purchase common stock associated with June 2016 Public Offering		—		421,867
Warrants to purchase common stock associated with March 2018 Public Offering - Series 2		798,810		798,810
Warrants to purchase common stock associated with December 2019 Public Offering		—		4,472,205
Warrants to purchase common stock associated with December 2020 Public Offering - Series 1		—		6,800,000
Warrants to purchase common stock associated with December 2020 Public Offering - Series 2		6,800,000		6,800,000
Prefunded warrants to purchase common stock associated with December 2020 Public Offering		3,200,000		5,260,000
Warrants to purchase common stock associated with Solar loan agreement		—		12,243
Warrants to purchase common stock associated with Loan Agreement		170,410		—
Warrants to purchase common stock associated with Danforth		50,000		—
For possible future issuance for the conversion of the March 2019 Notes		1,138,200		1,138,200
For possible future issuance for the conversion of the April 2020 Notes		—		1,299,790
For possible future issuance under 2014 Equity Incentive Plan  (Note 13)		295,220		146,488
For possible future issuance under Employee Stock Purchase Plan (Note 13)		3,893		5,895
For possible future issuance under 2015 Inducement Award Plan (Note 13)		235,000		14,050
Total common shares reserved for future issuance		14,367,493		28,028,978