# Deploying and Examining Beacon for At-Home Patient Self-Monitoring with Critical Flicker Frequency

## TL;DR

This paper describes a device called Beacon that allows patients to monitor cognitive function at home using flicker frequency, and reports on its use and feedback from patients and doctors.

## Contribution

The paper introduces Beacon, a novel at-home cognitive monitoring device using critical flicker frequency, and evaluates its practical use and user feedback.

## Key findings

- Measurements with Beacon remained stable across different times and environments.
- Patients and hepatologists provided feedback on Beacon's usability and data presentation preferences.
- Caregivers play a significant role in helping patients manage their condition using Beacon.

## Abstract

Chronic liver disease can lead to neurological conditions that result in coma or death. Although early detection can allow for intervention, testing is infrequent and unstandardized. Beacon is a device for at-home patient self-measurement of cognitive function via critical flicker frequency, which is the frequency at which a flickering light appears steady to an observer. This paper presents our efforts in iterating on Beacon’s hardware and software to enable at-home use, then reports on an at-home deployment with 21 patients taking measurements over 6 weeks. We found that measurements were stable despite being taken at different times and in different environments. Finally, through interviews with 15 patients and 5 hepatologists, we report on participant experiences with Beacon, preferences around how CFF data should be presented, and the role of caregivers in helping patients manage their condition. Informed by our experiences with Beacon, we further discuss design implications for home health devices.