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Updated: Dec 6, 2025
High-Speed Magnetic Tweezers for Nanomechanical Measurements on Force-Sensitive Elements
Published on: May 12, 2023
Blink detection and magnetic force generation for correction of lagophthalmos, with specific regard to implant
Razek Georges Coussa1,2,3, Nikita Lomis3, Fares Antaki2,4
1Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.
Purpose:
The overall goal was to restore a normal and synchronous blink in unilateral lagophthalmos. We describe the biocompatibility profiling of a novel ferromagnetic implant used for electromagnetic eyelid force generation.
Methods:
A non-contact blink detection system and an electromagnetic stimulation system were designed and tested. A modified Lester-Burch speculum equipped with strain gauge technology was used in blinking force measurement. Samarium-cobalt magnets were prototyped and coated with parylene-C. Biocompatibility testing was performed using NIH/3T3 mouse fibroblast cells with MTT colorimetric assay cytotoxic quantification.
Outcome Measures:
Cellular viability and interleukin concentrations.
Results:
Our system was capable of detecting 95.5 ± 3.6% of blinks in various lighting conditions. Using our force measuring device, the difference between non-paralyzed and paralyzed orbicularis oculi (OO) for normal and forceful blinking closure was 40.4 g and 101.9 g, respectively. A 16.6 × 5.0 × 1.5 mm curved shaped samarium cobalt eyelid implant was successfully developed and showed a reproducible blink at 100 ms with full corneal coverage with external eyelid taping. Compared to gold weights, parylene-C coated samarium cobalt implants showed not only excellent cell viability (82.0 ± 4.9% vs. 88.4 ± 0.9%, respectively, p > .05), but also below detection threshold for pro-inflammatory marker concentrations (interleukin-6 < 2 pg/mL and interleukin-10 < 3 pg/mL).
Conclusions:
We demonstrated excellent in-vitro biocompatibility of our parylene-C coated samarium cobalt implants. We believe that our novel approach can improve the quality-of-life of affected individuals and provides new understanding of blinking biomechanics.
