Profile - Dr Timothy Constantinou

Dr Timothy Constandinou has been working on a technology to improve brain machine interfaces (BMIs) – which enable direct communication between the brain and an external device.

How are BMIs useful and what have you developed?

BMIs are a platform technology which enable the development of various neuroprosthetics: tools which can help people whose brains function normally but where the connections between function and body response are faulty in some way, for example people with spinal cord injuries. We’re developing an implantable BMI consisting of a chip connected to a microelectrode array, which records, detects and transmits data from a large number of neurons.

What are the challenges involved?

Firstly, it’s most useful to monitor signals from individual neurons, but an implanted microelectrode typically picks up signals from multiple neurons at close proximity. The second challenge is in extracting data. BMIs typically use Spike-sorting inventor’s corner a wireless means of transmitting data using electromagnetic waves to avoid breaking the skin and risking infection. However, this method limits the data rate to 10Mbits/second, as higher bandwidths need higher frequencies, which are absorbed by tissue. 10Mbits/second is sufficient for 30 parallel channels which is insignificant in comparison to the 100 billion neurons in the brain.

What’s your solution?

Our main innovation is conducting spike-sorting in hardware and at the front-end (within the implant). Spike sorting determines which neuron generates each spike (within a single channel). The key information is which neuron fires and when. Usually neuroscientists conduct offline spikesorting using computer algorithms to determine this but we have developed spike-sorting hardware within the implant. Our chip can sort spikes in real time, so the BMI need only transmit spike-sorted data, enabling us to look at thousands of neurons simultaneously. Recent studies show signals recorded from 100 neurons can control a robotic arm sufficiently to facilitate self-feeding.

— Gavin Reed, Imperial Innovations