Income taxes - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Income taxes
Income tax expense	$ 0	$ 0
Research and development credits	42,220		$ 42,220
Increase (decrease) in valuation allowance	6,200,000	700,000
Uncertain tax positions	100,000	$ 100,000
Foreign
Income taxes
Operating loss carryforwards	143,300,000
United States
Income taxes
Operating loss carryforwards	85,400,000
State
Income taxes
Operating loss carryforwards	$ 91,800,000