It seems the last has not been heard of Elon Musk’s implantable chip company, Neuralink, as the company has recently raised $43 million to further its goal of making brain-implanted chips.

According to a filing published by the Security and Exchange Commission (SEC) recently, Neuralink’s funding gained, moving from its initial $280 million to $323 million, showing that $43 million was raised rather quietly, out of public scrutiny. The funds were raised from thirty two undisclosed investors.

Neuralink was founded in 2016, and is working on a device that can attach chips to the brain, as well as the chip itself. The company recently made a device capable of implanting ultra-thin threads inside the brain. In May, Neuralink received FDA approval to commence human trials, after going through series of disapprovals. The company recently opened an application channel to admit volunteers to its clinical trial program.

In the meantime, reports have it that Neuralink has been under series of scrutiny emerging from work ethics and the way animal test subjects have been treated, mostly unfairly. One of such scrutiny involved an investigation by the U.S. Department of Agriculture (USDA) over the welfare of animals used by Neuralink for its tests. The investigation was later squashed due to lack of evidence.

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The company has also been involved in some internal conflict that led to the departure of more than half of its scientists. Musk was accused of undermining management staff by asking junior staffers to email him directly about complaints and issues – this did not sit well with management, and resulted in what was termed as “internal conflict in which rushed timelines clashed with the slow and incremental pace of science.”

Neuralink has not publicly disclosed its valuation, however, a report published by Reuters in June valued the company at about $5 billion.