Subsequent events (Details) - USD ($)	1 Months Ended		9 Months Ended
	Oct. 31, 2021	Oct. 18, 2021	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Subsequent Event [Line Items]
Preferred Stock, Par or Stated Value Per Share			$ 0.01		$ 0.01
Proceeds from issuance of common stock, net of issuance costs				$ 14,982,663
2020 ATM Offering [Member]
Subsequent Event [Line Items]
Stock issued during period, shares, new issues	680,000
Proceeds from issuance of common stock, net of issuance costs	$ 1,500,000
Gross proceeds from sale of common stock	$ 1,548,000
Healthcare-focused Institutional Investor [Member] | October 2021 Offering [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Stock issued during period, shares, new issues		150,000
Convertible preferred stock		7,500,000
Preferred Stock, Par or Stated Value Per Share		$ 100
Conversion preferred stock per share		$ 2.00
Proceeds from issuance of common stock, net of issuance costs		$ 13,900,000
Gross proceeds from sale of common stock		$ 15,000,000.0
Class of warrant or right, exercise price of warrants or rights		$ 2.05
Warrants exercisable period		6 months
Warrants expiry period		5 years
Healthcare-focused Institutional Investor [Member] | October 2021 Offering [Member] | Subsequent Event [Member] | Warrants [Member]
Subsequent Event [Line Items]
Stock issued during period, shares, new issues		7,500,000