PORTEFEUILLE

Chronic wounds such as venous and diabetic foot ulcers are regarded as a silent epidemic, which affects 1 - 2 % of the population and represent 2 - 4 % of healthcare expenses. Correlated with age and the concurrent augmentation in comorbidities such as obesity, cardiovascular diseases and diabetes, they pose an increasing burden to the healthcare system. Despite the proliferation of new guidelines and therapies, chronic wound management remains extremely challenging. First, available wound assessment methods based on visual signs and symptoms provide limited accuracy and strongly rely on the practitioner’s experience. Second, modern wound care technologies acknowledgedly lack sufficient evidence of their impact to objectively support their utilization. As a consequence, wound care efficacy is hindered by non-optimal treatment decisions that rely on trial-and-error approaches and unnecessary medical interventions.

To address these issues, the TheranOptics project, in collaboration with EPFL, Empa and medical experts from the SUVA and HUG, aims at developing a new bioanalytical platform to empower evidence-based medicine in chronic wound care. Our approach relies on fiber-optic sensors as a highly flexible, low-cost device for remote monitoring of the patient’s wound exudate. We exploit recent advances in lab-on-fiber technology to develop an integrated bioanalytical platform, which combines microfluidics, electronics and optics functionalities in a single fiber. The device will be implemented with sensing chemistry specifically developed for wound diagnosis, providing the first bedside bioanalytical tool to support chronic wound management decisions.

This project proposes a unique combination of technology modules to achieve unmatched functionalities. Microstructured fibers are used as optofluidic module, and modified to integrate optoelectronic functionalities through the incorporation of semiconductor and metal elements in the preform material. This design allows for highly sensitive fluorescence assays in a fully integrated format. Compared to conventional lab-on-chip devices, this unique lab-in-fiber sensing platform possesses the desirable features of small size, potential for low manufacturing cost, and remote monitoring that make it highly advantageous for point-of-care testing.

In the first part, we used thermal drawing for the fabrication of several meters of hollow core fibers with integrated photodetecting capability. These fibers were successfully used as a reusable cylindrical fluorescence reader for the insertion and read-out of sensing capillaires. A portable controller prototype was finally developed based on an Arduino board and standard LEDs as light sources.

In the second part, hollow fiber capillaries were used as disposable optofluidic devices for the sampling and analysis of liquid samples. 3D printing was used for the automated fabrication of preforms with sophisticated architectures. After thermal drawing, the obtained capillaries were modified with sensitive coatings specific to the analyte of interest, such as a pH-sensitive fluorescent sol-gel film.

As an alternative, a major opportunity arose from the possibility to incorporate porous biopolymers in the thermal drawing process. This capacity enables the direct integration of sensing chemistry at the preform stage for the direct production of sensing capillaries without cumbersome post-modification steps. The process demonstrated to be compatible for the encapsulation of certain enzymes and enzyme substrates, thus unlocking the access to a wide range of bioassays inside our lab-in-fiber platform.

Last, the upscaling potential of our approach was demonstrated by the production of hundreds of pH-sensitive capillaries from a single drawing step. A 2-year follow-up project is starting in 2019, focusing on the integration and testing of novel sensing chemistry.

First publication for the lab-in-fiber platform planned in 2019.