Property, plant and equipment, net (Details) - USD ($)	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Subtotal	$ 7,675,855	$ 7,853,456
Less: Accumulated depreciation	(5,571,908)	(5,375,544)
Property, Plant and Equipment, Net, Total	2,103,947	2,477,912
Buildings
Property, Plant and Equipment [Line Items]
Subtotal	5,228,347	5,631,049
Machinery and Production equipment
Property, Plant and Equipment [Line Items]
Subtotal	1,307,356	1,311,624
Electronic equipment
Property, Plant and Equipment [Line Items]
Subtotal	203,305	193,912
Office equipment
Property, Plant and Equipment [Line Items]
Subtotal	48,440	38,524
Automobiles
Property, Plant and Equipment [Line Items]
Subtotal	545,006	545,008
Construction in progress
Property, Plant and Equipment [Line Items]
Subtotal	$ 343,401	$ 133,339

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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