The Martlet-backed graphene technology developer added more than $5m to a series A round that now totals $21.3m and is aiming to boost product development.

Paragraf, a UK-based graphene electronics producer backed by aerospace manufacturer Marshall of Cambridge, has increased its series A round to £16.2m ($21.3m) having secured venture capital firm Draper Esprit as an additional backer.

The extension follows $16m in a July 2019 tranche led by Parkwalk Advisors, subsidiary of commercialisation firm IP Group, and backed by Cambridge Enterprise, Amadeus Capital Partners, IQ Capital, Partners Investment Company and assorted angel investors.

Founded in 2015, Paragraf has developed a mass-production technique for processing…