Nantero has raised $21 million in funding for its carbon nanotube memory devices, which are an alternative to mainstream semiconductor chips.

The Woburn, Mass.-based company makes nonvolatile random access memory (NRAM), which can be used in a variety of products, such as smartphones, tablets, enterprise systems, and notebook and desktop computers, as well as applications in the automotive and industrial markets.

Globespan Capital Partners was the lead investor in the round, which also included participation from new and existing strategic and financial investors.

“The customer traction we’ve achieved at Nantero has been overwhelming, as evidenced by our recent announcement that NRAM had been selected by both Fujitsu Semiconductor and Mie Fujitsu Semiconductor,” said Greg Schmergel, cofounder and CEO of Nantero, in a statement. “With this additional funding, we will be able to help these existing customers speed their time to market while also supporting the many other companies that have approached us about using Nantero NRAM in their next generation products.”

The chips based on this super-fast and dense technology can be used in a wide array of markets, and can replace flash memory or dynamic random access memory. In the future, Nantero expects to be able to store terabits of data on a single memory chip.

They also have thermal and electrical conductivity properties that are better than from any other materials. The NRAM chips are low cost, and their components can be stacked. They can read or write data about 100 times faster than NAND flash memory and at about the same speed as dynamic random access memory (DRAM), the mainstay storage for gadgets, while the power is turned on.

But the challenge is getting them to mass production and high densities.

Nantero currently has more than a dozen partners and customers in the consumer electronics, enterprise systems, and semiconductor industries actively working on NRAM. The new funding will enable the company to support these partners in bringing multiple products into the market, while also enabling new customers to begin development. This financing round brings the total invested in Nantero to over $110 million.

“This round enables Nantero to accelerate its pace in product development, especially of its multi-gigabyte DDR4-compatible memory product,” said David Poltack, managing director at Globespan Capital Partners, in a statement. “Nantero has multiple industry-leading customers who would like to receive NRAM even sooner. The fact that several of these customers, as well as key partners in the ecosystem, have decided to also invest in Nantero is a strong sign of confidence, given how well they know Nantero and its product from years of working together.”

The company was founded in 2008, and it has 70 employees.