Development of a wearable fluorescence sensor for non-invasive monitoring of gut permeability

Abstract

Inflammatory bowel disease, coeliac disease, and malnutrition have all been linked to changes in intestinal function, particularly gut permeability [1]. Endoscopic biopsies and histopathology, together with chemical tests such as Lactulose:Mannitol assays, are the techniques currently used to assess permeability in the clinic. However, those methods are either invasive, unable to offer comprehensive diagnoses, or challenging to perform in infants [2]. Further, the mechanisms and in interactions behind function the the gut’s aforementioned (and additional) disorders are currently not well understood. As a result, novel diagnostic technologies that provide non-invasive and accurate measurements of intestinal permeability (and other aspects of gut function) could have major therapeutic implications [3]. Recent studies in both humans and animals have shown the potential of transcutaneous fluorescence spectroscopy to provide information relevant to gastrointestinal (GI) function – including gut permeability – in a non-invasive manner (e.g. [4-7]). This method entails oral administration of a fluorescent contrast agent combined with the use of a wearable probe to non-invasively measure the permeation of the contrast agent from the gut into the blood stream, thereby facilitating measurements of gut leakiness/permeability and other clinically relevant GI functions [4-7]. However, the devices that have been used for this purpose are laser-based, large and expensive, which make them unsuitable for large scale clinical deployment [4-7].To address the above limitations, here we report preliminary results from a compact fluorescence spectroscopy sensor for transcutaneous monitoring of gut function. The primary functionality of the device is to detect fluorescence signals at the skin as an orally ingested contrast agent (fluorescein) permeates through the gut barrier into the blood stream. For the developed sensor, the optical system, electronic design, and optical and temperature safety assessments are reported below, along with preliminary results demonstrating the potential for clinical use.