ResearchGate CEO Ijad Madisch. ResearchGate ResearchGate, the social media network for scientists, announced on Tuesday that it quietly raised $52.6 million (£42.3 million) from a cohort of big name investors in November 2015 to help it scale its business.

Goldman Sachs, the Wellcome Trust, and Bill Gates all put money into the Berlin company, which has over 12 million scientists on its platform, including thousands of researchers from the likes of Google and Facebook.

The nine-year-old company, which allows scientists to give each other feedback and work together on projects, has now raised over $87 million (£70 million).

When Business Insider asked why ResearchGate didn't announce the funding round in 2015, CEO and founder Ijad Madisch said: "I didn't really want to announce it because I think talking about funding generally is pretty boring. I prefer talking about the impact rather than raising money."

ResearchGate is announcing the funding now because it has disclose the capital it received in 2015 to the German government.

"The reason I’m doing it is because in Germany you have to submit your financials annually," said Madisch. "Now we have to submit 2015 financials."

The money has been used to build out ResearchGate's computing infrastructure, which is largely based in a data centre in Toronto, Canada. Some of it has also gone towards more than doubling ResearchGate's team size from 120 in 2015 to over 300 today, and a new office seems to be next on the agenda.

"The money is also for potential expansion in a new country which isn't Germany," said Madisch. "We cannot reveal yet because we have to decide where we want to go."

Madisch said the expansion is likely to be to another European country or the US, adding that he expects it to happen at some point within the next 15 months.

Microsoft cofounder Bill Gates has invested in ResearchGate. Ramin Talaie/Getty Images ResearchGate makes money by selling advertising space for scientific products, services, and jobs on its platform. "We're going to expand ads to host more different types of content," said Madisch, adding that there's "a lot to do in terms of connecting industry to scientists.

"We think we can build a scientific network and finance it through ads and not through letting people pay for access to content."

The CEO, who is also a qualified doctor, could not be drawn on ResearchGate's revenues but he said he expects to "break even" with this funding round. "We have always grown very carefully," said Madisch. "We’re always very diligent about how to raise the money and where to go next. My gut feeling tells me we don't need more money [after this]."

Ian Friedman, cohead of Goldman Sachs investment Partners Venture Capital & Growth Equity team, said in a statement: "The way in which the scientific community innovates is rapidly evolving away from siloed experimentation and toward network-driven collaboration. With its member network of 12 million individuals, ResearchGate has clearly become the dominant player driving that transformation.

"Partnering with a team leading the change in something as important as the way in which research is conducted is a rare opportunity and we're excited to support ResearchGate in fulfilling their mission of accelerating the pace of scientific advancement."