Equity Incentive Plans (Tables)

12 Months Ended

Dec. 31, 2023

Equity Incentive Plans [Abstract]

Stock Option Plan Activity

Activity under the stock option plans was as follows:

				Weighted
				average
	Number of			exercise
	options			price
Outstanding at December 31, 2021		689,995		$	3.58
Granted		367,670			5.33
Exercised		(9,445	)		1.71
Expired		(10,558	)		27.00
Forfeited		(106,112	)		4.09
Outstanding at December 31, 2022		931,550		$	3.97
Granted		1,301,200			0.59
Forfeited		(130,720	)		1.97
Outstanding at December 31, 2023		2,102,030		$	2.00
Vested and exercisable at December 31, 2023		1,226,458		$	2.65

Stock options granted under the 2021 Plan for the years ended December 31 2023 and 2022 were as follows:

	2023		2022
Employee		1,211,200		299,670
Nonemployee		90,000		68,000
Total		1,301,200		367,670

Black-Scholes Weighted Average Assumptions

The Black-Scholes weighted average assumptions for all stock option awards granted during 2023 and 2022 were as follows:

	2023			2022
	2021 Plan			2021 Plan			Inducement Grants
Fair Value of Awards	$	0.48			2.06			2.01
Grant Price	$	0.59			5.33			2.42
Expected term (in years)		5.63			6.28			6.25
Risk‑free interest rate		4.09	%		2.13	%		2.52	%
Dividend yield		—	%		—	%		—	%
Expected volatility		105.33	%		107.98	%		107.70	%

Options Outstanding and Vested and Currently Exercisable by Exercise Prices

The options outstanding and vested and currently exercisable by exercise prices as of December 31, 2023 were as follows:

Options outstanding						Options vested and exercisable
				Weighted				Weighted		Weighted
				average		Number of		average		average
Exercise		Outstanding		remaining		options		Exercise		remaining
price		(in shares)		life years		vested		price		life years
$	0.47 - 0.48		3,200		9.50		—	$	—		—
	0.49 - 0.53		1,061,600		9.50		601,400		0.49		9.51
	0.54 - 1.61		186,000		9.15		51,725		1.50		8.44
	1.62 - 1.74		193,335		2.21		82,224		1.71		2.21
	1.75 - 3.14		196,242		8.61		29,456		2.96		8.10
	3.15 - 3.6		259,836		3.50		259,836		3.24		3.50
	3.61 - 13.00		201,817		6.52		201,817		8.97		6.52
			2,102,030		7.69		1,226,458		2.65		7.17

Share-based Compensation Expense

The following table shows the stock-based compensation expense related to vested stock option grants to employees and non-employees awarded under the stock plans and inducement grants by financial statement line item on the accompanying statements of comprehensive loss:

	2023			2022
Research and development	$	159,816			95,484
Sales and marketing		(948	)		6,680
General and administrative		516,832			122,775
Total share-based compensation expense	$	675,700			224,939