Novel carbon dioxide wound sensors for pathogen detection and therapeutic monitoring

  • Erin Magee

Student thesis: Doctoral ThesisDoctor of Philosophy


The treatment and management of chronic wounds presents a significant challenge to modern healthcare. Evidence now supports microbial biofilms as a key deterrent to healing, with their presence occurring in up to 80% of non-healing wounds.

In this thesis, a novel sensor was developed to offer 24/7, non-invasive monitoring of wound infection to overcome the shortcomings of current wound care and provide an early warning to infection development and unsuccessful treatment. The sensor monitors the headspace that exists between the wound and dressing for small increases in CO2, which is ubiquitously produced from aerobic microorganisms.

A formulation containing LDPE, xylenol blue dye, and tetrabutylammonium hydroxide was 3D printed to form a CO2-sensitive indicator film and tested against a range of common wound pathogens in an ex vivo porcine skin wound dressing model. The film changed colour from blue to yellow in response to wound infection. The time taken to reach an intermediate colour change was found to be directly proportional to the time taken for the microbial load to exceed 106 CFU/mL, regardless of initial inoculum. In addition, this colour change occurred before a measurable increase in biofilm biomass, indicating that this sensor acts as an early warning to biofilm development.

The ability of the sensor for monitoring treatment efficacy was also assessed by treating P. aeruginosa biofilms with antibiotic monotherapy, phage cocktail monotherapy, or a combination of both. A greater log-fold reduction in P. aeruginosa following treatment was complemented by longer sensor response times. Sensors monitoring biofilms exposed to suboptimal antibiotic or phage concentrations changed colour, whilst successfully treated biofilms elicited no colour change.
This sensor has the potential to aid wound care by allowing successfully treated wounds to heal undisturbed, prompting further intervention for failing treatment, and reducing costs and time dedicated to dressing changes.
Date of AwardJul 2022
Original languageEnglish
Awarding Institution
  • Queen's University Belfast
SponsorsNorthern Ireland Department for the Economy
SupervisorBrendan Gilmore (Supervisor) & Andrew Mills (Supervisor)


  • Biofilm
  • wound infection
  • smart dressing
  • infection biomarker

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