"At the moment we are using precise but cost-effective manufacturing techniques for the plectra and casing and anticipate that remaining parts will be moulded industrially, slashing the cost. I'd put a cost tag of less than £10 for each harvester on a large scale production."

The research has been presented today in IOP Publishing's journal .

This week's bizarre inventions also include a solar-powered, phone-charging "Booster Brolly", developed by mobile operator Vodafone. The new gadget is capable of charging a handset in three hours through its flexible solar panels, placed in the umbrella's canopy.

Designed in partnership with the University College London, the wind and waterproof contraption will be trialled at the upcoming Isle of Wight music festival.