The Design, Implementation, and testing of a sensorized MRI-compatible Cello

Abstract

The design and testing of optical sensors for a cello compatible with magnetic resonance imaging (MRI) are presented. The interface is used in neuroimaging experiments, allowing for the first time, the acquisition of cello performance gestures captured inside the MRI scanner. Left-hand fingering and right-hand bowing gestures were captured with optical sensors embedded in the fingerboard, bridge, and bow. Finger-string interaction was sensed through diffuse reflection using plastic optical fibres potted in a 3D-printed fingerboard. Acoustic string vibration was sensed through the transmissive amplitude modulation of an emitting-receiving fibre pair mounted in a specially designed bridge. Bow position and force was transduced with a combination of optical sensors, including optical flow, macrobending loss under compressive strain, and with a three-axis Faraday rotator. The sensors provided sufficient resolution and dynamic range to measure cello gestures inside the MRI scanner, and no interference from the scanner was noted in the acquired signals. Further MRI compatibility testing confirmed that the interface and sensors had no meaningful effect on field homogeneity and no image artifacts were noted. The interface is currently being used in neuroscience experiments.