PupilMetrix: Automated Pupil-Based Clinical Phenoptyping for Sleep and Mood Disorders

Though the importance of circadian biology to health is understood, clinical tools for evaluating circadian health are lacking. Currently, no commercially available device can measure an individual’s circadian (non-visual) sensitivity to light. Our clinical partners developed a proof-of-concept instrument in the lab based on a collection of six separate off-the-shelf scientific components. These components were expensive, difficult to set up and operate (requiring specialist training), difficult to scale, and unreliable. Understanding an individual's risk score for circadian disruption enables innovation in sleep research and clinical care. Developing an automated, easy-to-use, device was essential to scale this innovation.

The PupilMetrix device integrates a series of sensors and light stimulators into a seamless device capable of automating the creation of a score for circadian light sensitivity. We have reduced a complex system of expensive parts to simple printed circuit boards. Through miniaturisation we have been able to produce a head-mounted device, simplifying the process of placing the sensors accurately and ensuring the device works as people move and look around. It was critical to keep the two eyes separate, this created a complex ergonomic challenge of sealing around each eye for a range of face shapes and sizes.

PupilMetrix is being used for research to advance the scientific understanding of individual variability in circadian sensitivity. We are batch-producing devices in-house at SensiLab for other labs domestically and internationally. Circadian disruption has been known to be an underlying aspect of nearly all chronic diseases with wide-reaching implications for future care. We have redesigned a complex piece of lab equipment, requiring a large dark room, into something that can be used directly in sleep clinics. We have focused on producing an easy-to-use device that can easily and effectively scale from the lab to the clinic.

One of the key design considerations was preventing the light stimulus from leaking from one eye to the other. This required very ergonomically refined eyepieces that allow for a tight seal around each eye. These are carefully designed to allow for variance in face shape and size and are cast in a soft expanding foam material. A unique foam casting process using 3D printed moulds was developed to iteratively refine and test this geometry, in a compliant foam material. The design features a quick and easily adjustable seamless strap mechanism allowing for quick and simple set-up from one user to the next. Cables are cleverly managed in the strap. Custom electronics design was essential to miniaturising the sensor systems into something small enough to build a comfortable head-mounted system around. While advanced computer vision algorithms ensure the testing and analysis process can be completely automated. These innovations add up to a device that is seamless to use, that can be used in a wide range of contexts and is comfortable for the recipient.