title: Design and implementation of a wireless capsule suitable for autofluorescence intensity detection in biological tissues.
abstract: We report on the design, fabrication, testing, and packaging of a miniaturized system capable of detecting autofluorescence (AF) from mammalian intestinal tissue. The system comprises an application-specific integrated circuit (ASIC), light-emitting diode, optical filters, control unit, and radio transmitter. The ASIC contains a high-voltage charge pump and single-photon avalanche diode detector (SPAD). The charge pump biases the SPAD above its breakdown voltage to operate in Geiger mode. The SPAD offers a photon detection efficiency of 37% at 520 nm, which corresponds to the AF emission peak of the principle human intestinal fluorophore, flavin adenine dinucleotide. The ASIC was fabricated using a commercial triple-well high-voltage CMOS process. The complete device operates at 3 V and draws an average of 7.1 mA, enabling up to 23 h of continuous operation from two 165-mAh SR44 batteries.
authors.affiliation: School of Engineering, University of Glasgow, Glasgow, G12 8LT, UK. m.al-rawhani.1@research.gla.ac.uk
authors.forename: Mohammed A
authors.initials: MA
authors.lastname: Al-Rawhani
authors.forename: Danial
authors.initials: D
authors.lastname: Chitnis
authors.forename: James
authors.initials: J
authors.lastname: Beeley
authors.forename: Steve
authors.initials: S
authors.lastname: Collins
authors.forename: David R S
authors.initials: DR
authors.lastname: Cumming
mesh_terms: D000818:Animals; D053704:Capsule Endoscopy / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D008954:Models, Biological; D061848:Optical Imaging / Q000379:methods*; D017785:Photons; D012756:Sheep