Contact Lens Accelerometer Network for Eye Tracking
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Solution Overview
Problem
Conventional eye tracking components for eye-mounted displays are large and cumbersome, degrading the user experience and limiting their application in virtual and augmented reality, as well as other fields, due to their size and bulkiness.
Innovation Solution
A contact lens-based eye tracking system utilizing a network of small accelerometers and a magnetometer to estimate eye position and orientation, with optimized geometries such as shortened tetrahedrons and non-planar arrangements of 3-axis and 2-axis accelerometers, allowing for compact and unobtrusive eye motion monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional eye tracking components are used, then eye tracking functionality is achieved, but the system becomes large and cumbersome
Solution Approach 1:
The eye tracking system is segmented into two parts: small sensor arrays (accelerometers and magnetometers) integrated into the contact lens for eye motion detection, and a separate processing unit that receives data from the sensors. This segmentation allows the critical sensing function to be miniaturized and worn on the eye, while the bulkier processing components can be located elsewhere.
Solution Approach 2:
The patent embeds multiple sensor types (accelerometers and magnetometers) within the same contact lens structure, creating a nested configuration where different sensing functions are integrated into a single wearable platform. This nesting approach consolidates multiple functions into one compact unit, reducing overall system volume.
2Reliability
If conventional eye tracking components are used, then eye tracking functionality is achieved, but the user experience is degraded
Solution Approach 1:
By segmenting the eye tracking function into tiny sensors that can be worn directly on the contact lens, the system becomes much less obtrusive and more comfortable for users. The separation of sensing (on the eye) from processing (external) allows the user to experience minimal burden while maintaining full functionality.
Solution Approach 2:
The patent places the sensing components locally at the eye where they are needed, using contact lens-integrated sensors that detect eye motion directly at the source. This local placement improves measurement accuracy and user comfort compared to external tracking systems that require line-of-sight or physical contact with the face.
3Volume of moving object
If smaller sensor arrays are used in the contact lens, then the system becomes more compact, but measurement precision may be affected
Solution Approach 1:
The patent combines multiple types of sensors (accelerometers for linear acceleration and magnetometers for magnetic field orientation) into a unified sensor array within the contact lens. This merging of different sensing modalities compensates for the limitations of individual sensor types, maintaining measurement precision despite the reduced size of each individual sensor.
Solution Approach 2:
The sensor array uses a composite approach by integrating different sensor technologies (accelerometers and magnetometers) that measure different physical quantities. This composite sensing strategy allows the system to achieve accurate three-dimensional eye position and orientation tracking using smaller overall sensor packaging compared to single-type sensor arrays.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate and power-efficient eye motion tracking, enhancing user experience and application versatility by maintaining projected images stationary relative to the external environment, while being small and unobtrusive.
Implementation Method 1
a contact lens containing an accelerometer network
Implementation Method 2
one or more very small projectors (referred to as femtoprojectors) contained inside the contact lens
Data Source
AI summary
In one approach to eye tracking, a contact lens contains a network of twelve accelerometers. The accelerometers are positioned within the contact lens so that the measurements of acceleration can be used to estimate a position and an orientation of the eye relative to an external reference frame. One advantage of accelerometers is that they can be made relatively small and do not require much power. However, because the contact lens has a curved shape and is relatively thin, the possible locations for the accelerometers are limited. Various geometries for the accelerometer network and approaches to optimizing these geometries are described.