Stock option plans - Restricted stock units (Details) - Restricted stock units - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Unrecognized compensation cost related to RSU	$ 243,709
Recognition period for unrecognized compensation cost	2 years 7 months 6 days
Restricted stock units
Beginning balance (in shares)	19,985
Granted (in shares)	24,064	26,150
Vested (in shares)	(30,981)	(5,365)
Cancelled/Forfeited (in shares)	(334)	(800)
Ending balance (in shares)	12,734	19,985
Weighted average grant date fair value
Beginning balance, Weighted average grant date fair value	$ 118.20
Granted, Weighted average grant date fair value	28.68	$ 118.20
Vested, Weighted average grant date fair value	88.21	118.80
Cancelled/Forfeited, Weighted average grant date fair value	114.60	120.00
Ending balance, Weighted average grant date fair value	$ 21.80	$ 118.20
Executive officers
Restricted stock units
Granted (in shares)	9,320
Executive officers and certain other employees
Restricted stock units
Granted (in shares)	11,330	25,000
Cancelled/Forfeited (in shares)		(800)
Non employee directors
Restricted stock units
Granted (in shares)	3,418	1,152
Vesting period	1 year
Vesting On One Year Anniversary Of Grant Date | Executive officers
Restricted stock units
Vesting period	1 year
Vesting On One Year Anniversary Of Grant Date | Executive officers and certain other employees
Restricted stock units
Vesting period	1 year
Vesting On Two Year Anniversary Of Grant Date | Executive officers
Restricted stock units
Vesting period	2 years
Vesting On Two Year Anniversary Of Grant Date | Executive officers and certain other employees
Restricted stock units
Vesting period	2 years
Vesting On Three Year Anniversary Of Grant Date | Executive officers
Restricted stock units
Vesting period	3 years
Vesting On Three Year Anniversary Of Grant Date | Executive officers and certain other employees
Restricted stock units
Vesting period	3 years