Income taxes - Income Taxes Rate Reconciliation (Details) - USD ($)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Reconciliation, amount
Tax at U.S. statutory rate	$ (2,646,101)
Others, Foreign tax effects	1,024
Research and development credits, Tax credits	(42,220)
Changes in valuation allowance	2,592,855
Nontaxable and nondeductible items	20,946
Other adjustments, Changes in unrecognized tax benefits	73,496
Effective tax rate	$ 0	$ 0
Reconciliation, percent
Tax at U.S. statutory rate	21.00%	21.00%
Others, Foreign tax effects
Research and development credits, Tax credits	0.30%
Permanent differences		(0.10%)
Changes in valuation allowance	(20.60%)	(19.70%)
Nontaxable and nondeductible items	(0.20%)
Other adjustments, Changes in unrecognized tax benefits	(0.50%)
Other adjustments		(1.20%)
Effective tax rate	0.00%	0.00%
Tax Jurisdiction of Domicile [Extensible Enumeration]	UNITED STATES