Income taxes - Net long-term deferred tax liability (Details) - USD ($)	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
Research & development tax credits	$ 398,413	$ 613,003
Loss carry forward	300,545	0
Accrued compensation	112,446	110,092
Valuation allowances	(139,207)	(496,343)
Deferred Tax Assets, Net of Valuation Allowance	672,197	226,752
Deferred tax liabilities:
Property and equipment	254,301	252,800
Intangible assets	982,422	1,188,009
Deferred Tax Liabilities, Gross	1,236,723	1,440,809
Net deferred tax liability	564,526	1,214,057
Discontinued Operations
Deferred tax assets:
Operating loss carryforwards - Mexico	4,230,398	4,296,453
Land basis difference - Mexico	1,602,470	1,262,159
Start-up costs - Mexico	4,693,395	4,904,337
Valuation allowances	(10,526,263)	(10,462,949)
Deferred Tax Assets, Net of Valuation Allowance	$ 0	$ 0