Nicholas Trigger - CLABSI Prevention Device

D. Bearden · D. Chong · N. Kodua · F. Rudd · N. Trigger|Dept. of Biomedical Engineering, Duke University

Shutoff Time

17 ms

450 ms limit (ISO 15858)

CFU Reduction

4-log

EPA OCSPP 810.2200

Device Weight

204 g

One-handed operation

UV-C Bandwidth

263–273 nm

2.49 ± 0.047 mW optical

Problem & Need

Central Line-Associated Bloodstream Infections (CLABSIs) occur when bacteria enter the bloodstream via a central line. 40,000 CLABSIs occur annually in the US, costing hospitals approximately $1.9B per year, and 65–70% are completely preventable with proper disinfection.

The current standard of care is the Scrub-the-Hub technique, which relies entirely on nurse compliance with manual protocol. Infections arise from human error and inconsistent adherence to workflow. This device removes that dependency.

Need Statement: Hospital nurses need a quick, reliable, and user-friendly system to disinfect central lines to maintain adherence to proper protocols and reduce infection risk in patients.

Why UV-C Disinfection?

DNA and RNA strongly absorb 260 nm UV-C incident light. The high-energy photons create nitrogenous base lesions, distorting the helix structure and blocking transcription and translation, effectively sterilizing the hub surface without chemicals, contact, or manual technique.

Device Design

Mechanical

The enclosure is resin-printed to prevent UV-C light leakage. Key mechanical elements:

#	Component	Role
1	Resin-Printed Casing	Contains UV-C, prevents leakage
2	Disinfection Chamber	Where the catheter hub is inserted
3	RGB LED	Color-coded status during operation and errors
4	Activation Button	Single-button start/abort
5	Opening Aperture	Seals around the catheter to prevent leakage
6	Safety Interlocks (×2)	Abort if device opens prematurely

Electrical

Three custom KiCad PCBs make up the electrical system:

Board	Function
Main	nRF54L15 MCU, power management, BMS (MAX17260), RGB LED driver (LP5815)
UVC	UV-C LED driver with current-limiting elements
Base	Mechanical base and connector board

Firmware

Written in C on Zephyr RTOS (nRF Connect SDK), targeting the nRF54L15. The application runs a hierarchical state machine (Zephyr SMF):

INIT → IDLE ──► DISINFECTING ──► IDLE
            ──► CHARGING      ──► (abort via button or interlock)
            ──► ERROR

State	Behavior
`INIT`	Initialize GPIO, PWM, I2C, BMS, safety interlocks
`IDLE`	Awaiting button press; battery SOC displayed on RGB LED
`CHARGING`	Charge in progress; RGB indicates charge level
`DISINFECTING`	UV-C LED at full PWM; instant abort on interlock open or button press
`ERROR`	RGB error pattern + buzzer; cleared by button press

The critical safety path: interlock GPIO interrupts submit a work item that disables PWM output before the SMF state transition completes, with a mean shutoff time of 17 ± 2 ms, well within the 450 ms safety limit derived from ISO 15858.

Testing Results

Metric	Value
Device Weight	204 g
UV-C LED Optical Power	2.49 ± 0.047 mW
UV-C LED Bandwidth	262.9 – 273.2 nm
Rapid Shutoff Time	17 ± 2 ms (limit: <450 ms)
Germicidal CFU Reduction	4-log reduction (n=3 replicates)

Germicidal testing used DH5α bacteria incubated, seeded, and adhered to catheter hubs at room temperature. Hubs were irradiated with UV-C at 0, 2, and 4 hours, then vortexed for CFU counts by serial dilution, achieving a 4-log reduction.

Regulatory & Market

The CLAB-Free device will be classified as a Class II FDA device given the inherent risk of UV light and catheter use. Two potential pathways:

510(k), Preferred: If determined similar enough to existing UV surface-disinfecting devices
De Novo: If disinfection through catheter tubing constitutes a novel use case

Total Available Market

~$1.61B

Global catheter-related bloodstream infection market (2024)

Serviceable Available Market

~$481M

US central-line infection market (minimum estimate)

Serviceable Obtainable Market

~$16.1M

5% of preventable CLABSIs

Conclusion & Next Steps

The device successfully disinfects central line hubs using UV-C light in the germicidal range, achieves a 4-log CFU reduction, and operates safely within ISO 15858 exposure limits. It is portable, one-handed, and reusable between patients.

Planned next steps:

Nurse usability testing
Design of docking/recharging stations
Autoclavable disinfection chamber redesign
Head-to-head testing against proper and improper Scrub-the-Hub technique

CLABSI Prevention Device