University of California, San Diego
Mechanical and Aerospace Engineering Department
MAE 156B - Senior Design Project
Dr. Darshan Patel, MD, a skilled urologist and assistant professor at the UCSD School of Medicine, identified a critical safety hazard in operating rooms caused by dangerously hot fiber optic cords used in laparoscopic, thoracoscopic, and arthroscopic surgeries. These cords, essential for delivering illumination to enclosed body cavities, can reach temperatures of 262°C, posing risks of severe burns to patients and fires when left unattended on top of patients. Instances of detached light cables resting on surgical drapes have resulted in full-thickness skin burns within mere seconds, endangering patients and staff while potentially leading to lawsuits and financial strain on hospitals. The LightLok project focuses on designing a retrofitted, autoclavable attachment that accommodates diverse light cord specifications, prevents thermal injuries, and ensures single-use safety—all without compromising surgical procedures' efficiency or sterility.
High Priority
Operates at full power for a minimum of 5 minutes
Contact surface temperature: Max 50°C (122°F)
Withstands temperatures up to 255°C (491°F)
Features an automatic closing mechanism after cord use
Capable of sterilization
Designed not to obstruct or interfere with surgical procedures
Second Priority
Single-use design
Universal fit (one-size-fits-all) for light cords
Fully assembled LightLok on Light Cord
Cord Clamp & Snap Latch
Lens Cap
Cord Clamp & Snap Latch Fitted
Lens Cap
The lens cap contains a plano-concave magnesium fluoride lens diverges the light, which reduces the light intensity and preventing thermal injury. It maintains surface temperatures below 50°C under maximum intensity power from the light cord.
Cord Clamp & Snap Latch Mechanism
An adjustable, snap-fit clamp securely attaches to various light cords, ensuring broad compatibility.
Filament & Print Time
Spring
Fused Silica Lens
Plot of temperature v. time of the LighLok's surface temperature with LightLok on the ligh cord.
Plot of temperature v. time of the drape's surface temperature with LightLok on.
Experimental Setup with LightLok
Placed the LightLok closed on the light cord and turned on the lightbox and set on standby for 5 minutes before use.
Then placed the LightLok on the surgical drape and checked temperature of the contact surface (drapes) every 30 seconds until 10 minutes.
Results with LightLok
The surface temperature reached a maximum of 48°C after 10 minutes.
The rate of temperature increase slowed after 4 minute mark.
Without LightLok, within 5 seconds, the surgical polypropylene drape burned
ASTM C1055
Safe touch temperatures—damage risk doubles with each °C rise above 44°C, 50°C safe for 5 minutes.
ISO 10993-1
Ensures medical device biocompatibility; the polycarbonate meets this standard.
ISO 17665
Validates sterilization processes; the polycarbonate complies.
For more information about LightLok, please see our executive summary page.