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We report the theory, construction, and testing of a flexible ocular, on-the-eye microsystem used for ultra-low power object distance sensing suitable for smart adaptive contact lenses. The microsystem determines object distance by vergence angle triangulation. Vergence angle is determined from passive measurements of the earth’s magnetic field at each eye. Vergence measurements were performed every 5-degree interval over 35 degrees in total for each eye to accommodate the entire human visual range. Vergence angle measurements had an RMS error of 1.74 degrees and a distance ranging RMS error of 14.04 mm. The energy requirement per magnetic field measurement was estimated to be approximately 2 μJ per eye.
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Low-Profile Induced-Voltage Distance Ranger for Smart Contact Lenses
Objective: We present a novel, low-profile, scleral-coil based, distance ranging system which is suitable for smart, accommodating contact lenses. Methods: We measure the induced emf between a set of four thin semi-circular coils patterned on flexible Kapton substrates that conform to the eyes’ sclera. This induced emf is a function of eye gaze angles. The distance from the eyes to the desired object is next determined via the triangulation of the eye gaze angles Results: Experiments on simulated tissue gel eyeballs indicate an accurate prediction of object distance in the 0.1-15 D (diopter) range with a 0.15 D RMS error and object direction in the -15 to 15-degree field of view with 0.4-degree RMS error, respectively. The energy required per range reading was determined to be as low as 20 μJ. Conclusion: Experimental data shows that the distance ranging system can accurately measure eye-gaze angles and object-distance with very low energy consumption. Significance: The high-accuracy, low-profile and reduced energy requirements make the distance ranger suitable for low-power vision corrective applications such as smart contact lenses.
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- Award ID(s):
- 1932602
- PAR ID:
- 10210569
- Date Published:
- Journal Name:
- IEEE Transactions on Biomedical Engineering
- ISSN:
- 0018-9294
- Page Range / eLocation ID:
- 1 to 1
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1109/TBME.2020.3040161
