Summary of significant accounting policies - Potentially dilutive securities (Details) - shares	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Potentially dilutive securities
Total shares of common stock equivalents	2,847,496	610,275
Convertible preferred stock (as converted)
Potentially dilutive securities
Total shares of common stock equivalents	28,112	28,112
Employee Stock Option [Member]
Potentially dilutive securities
Total shares of common stock equivalents	596,466	551,886
Warrants to purchase common stock
Potentially dilutive securities
Total shares of common stock equivalents	2,194,788
Unvested restricted stock units
Potentially dilutive securities
Total shares of common stock equivalents	28,130	30,277