UVC-Disinfecting Breast Expander

An implantable device inserted into existing breast expander, designed to address the high infection rates of breast reconstruction, with UVC LEDs controlled by an automatic timing scheme.

Problem Statement

Address high infection rates related to the use of the breast tissue expander in patients who have had a mastectomy and radiation therapy by reducing bacterial infection rates and improve tissue expander success.

User Needs and Specifications

Efficacy in Sterilization
1. 85% Illumination coverage
2. 2000mW⋅s/cm² Dosage of UVC on outside surface of silicone expander
3. 85% Sterilization of:
  1. Staphlyococcal aureus
  2. Pseudomonas aeruginosa
  3. Ralstonia bacteria
Electrical Components Insulated
1. Device stays within range of 5°C of the environment
2. Device functions in saline environment
Portability
1. Weight of the device ≤ 200 g
2. No external wires or components outside of the body
Imaging Compatibility
1. X-Ray and CT compatible
2. Ultrasound compatible
3. Does not cause magnetic interference

5. Compatibility with Breast Expansion

1. Fits smoothly inside the expander, without protruding edges
2. Compatible with magnetic port
3. Fully incorporated within the standalone breast expander

6. Durability

1. System is fully functional with ≤ 50 lb force/compression
2. Lasts up to 1 year in the body

7. Comfort

1. Comfortable weight distribution while standing and laying
2. Fits smoothly inside the expander
3. Causes no lasting imprints on tissue

8. Functional without Further Interaction

1. No patient interaction required
2. No further surgeries required
3. Lasts up to 1 year in the body

9. Cost

1. Materials cost below $250

Existing Solutions

The current prevention method involves sterilizing the expander before surgery. If infected, the patient can only be treated with antibiotics, and a worsening infection could require premature removal of the breast expander.

Relevant patent search:

US9808647B2 - Methods and apparatus to inactivate infectious agents on a catheter residing in a body cavity
US20150073396A1- Apparatus, method, and system for selectively effecting and/or killing bacteria
US9259513B2- Photocatalytic disinfection of implanted catheters
US20532219B2 - Apparatus for treatment of wounds and skin medical conditions at a predetermined skin area of a human body

Final Prototype

Enclosure Design

The 3-D printed enclosure includes strain-relief clamping for LED wires. The enclosure is printed using PLA and has a volume of 26mL. An O-ring around the rim of the disk ensures waterproofing.

Circuit Design

An ATtiny85 microcontroller controls the timing scheme. The PCB also includes pin headers for the battery port and 4 sets of 3 LEDS in parallel. Other components include a voltage regulator and NPN transistor.

Timing Scheme

The UVC lights will be turned on for 15 minutes twice a day, to kill approximately 96.18% of bacteria. The short 12 hour off period prevents bacterial growth from reaching a full medium layer, which can develop within 16 hours. The device will begin in the "off" stage to prevent accidental exposure to surgeons and hospital staff.

Surgeon Workflow

Testing

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