Related party transactions and balances (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Related party transactions included within interest expense:
Interest expenses on promissory notes issued to relatives of the Chairman and Chief Executive Officer of the Company	$ 83,457	$ 78,981	$ 162,749	$ 157,963
Interest expense on lines of credit payable to the Chairman and Chief Executive Officer of the Company and his spouse	392,593	355,715	777,515	670,452
Interest expense related to the modification of stock options held by the Chairman and Chief Executive Officer of the Company and his spouse related to financing provided		1,287,834		1,287,834
Related party transactions including within selling, general and administrative expenses:
Consulting fees to the Chairman and Chief Executive Officer of the Company accrued on the line of credit available to the Company	62,400	62,400	124,800	124,800
Consulting fees to a director of the Company settled with issuance of common stock	40,000		40,000
Salary for services as VP Corporate and director of the Singapore subsidiary to the spouse of the Chairman and Chief Executive Officer of the Company	10,890	11,254	21,981	11,254
Loss on settlement of debt to a relative of the Chairman and Chief Executive Officer of the Company		16,800		16,800
Rent paid to a company controlled by the spouse of the Chairman and immediate family members	$ 8,006		$ 20,206