Researchers used an event-based tactile sensor mounted on a robotic arm to scan a board containing the 26 English Braille letters. They converted the sensor’s signals into electrical stimulation delivered through eight electrodes beneath each human forebrain organoid, then classified the organoids’ spike responses with machine-learning methods.

A single organoid produced an average classification accuracy of 61%. Combining responses from three organoids raised accuracy to 83% and made the system more resistant to several types of artificially added noise.