Wireless fluorescence capsule for endoscopy using single photon-based detection

Abstract

Fluorescence Imaging (FI) is a powerful technique in biological science and clinical medicine. Current FI devices that are used either for in-vivo or in-vitro studies are expensive, bulky and consume substantial power, confining the technique to laboratories and hospital examination rooms. Here we present a miniaturised wireless fluorescence endoscope capsule with low power consumption that will pave the way for future FI systems and applications. With enhanced sensitivity compared to existing technology we have demonstrated that the capsule can be successfully used to image tissue autofluorescence and targeted fluorescence via fluorophore labelling of tissues. The capsule incorporates a state-of-the-art complementary metal oxide semiconductor single photon avalanche detector imaging array, miniaturised optical isolation, wireless technology and low power design. When in use the capsule consumes only 30.9 mW, and deploys very low-level 468 nm illumination. The device has the potential to replace highly power-hungry intrusive optical fibre based endoscopes and to extend the range of clinical examination below the duodenum. To demonstrate the performance of our capsule, we imaged fluorescence phantoms incorporating principal tissue fluorophores (flavins) and absorbers (haemoglobin). We also demonstrated the utility of marker identification by imaging a 20 μM fluorescein isothiocyanate (FITC) labelling solution on mammalian tissue.

Ultrasound capsule endoscopy: sounding out the future

“…To achieve this, µUS has been considered as the modality of choice. µUS frequencies are more typically a factor at least 1.5 times higher than standard clinical frequencies Development of the fluorescent imaging cube is being conducted by Al-Rawhani and colleagues and is detailed in a separate publication (14).…”

“…This includes microchip design, µUS array development, integration of the functional sub-elements and capsule shell functionalization. While conceived primarily as an US capable diagnostic capsule, other sensing modalities are under consideration, including fluorescent imaging (14). Development of therapeutic capsules is another area of active research (45 …”

Progress towards a multi-modal capsule endoscopy device featuring microultrasound imaging

“…Current FI systems are limited by physical bulk and power consumption and are thus not suitable for capsule endoscopy. Previous work has shown the viability of a miniaturised low-powered wireless FI capsule compact enough to examine the entire GIT, and exhibiting sufficiently low power consumption to operate from internal batteries over its entire journey through the GIT [10].…”

Nanotechnology in multimodal theranostic capsule endoscopy

“…In the work outlined here, fluorescence imaging was based on the configuration of single-photon avalanche diode (SPAD) arrays with bespoke application-specific integrated circuits (ASICs) in miniaturized configurations for capsule deployment [8]. Successful demonstrations of both imaging and miniaturization are demonstrated.…”