title: Detection and Monitoring of Microparticles Under Skin by Optical Coherence Tomography as an Approach to Continuous Glucose Sensing Using Implanted Retroreflectors.
abstract: We demonstrate the feasibility of using optical coherence tomography (OCT) to image and detect 2.8μm diameter microparticles (stationary and moving) on a highly-reflective gold surface both in clear media and under skinin vitro. The OCT intensity signal can clearly report the microparticle count, and the OCT response to the number of microparticles shows a good linearity. The detect ability of the intensity change (2.9% ± 0.5%) caused by an individual microparticle shows the high sensitivity of monitoring multiple particles using OCT. An optical sensing method based on this feasibility study is described for continuously measuring blood sugar levels in the subcutaneous tissue, and a molecular recognition unit is designed using competitive binding to modulate the number of bound microparticles as a function of glucose concentration. With further development, an ultra-small, implantable sensor might provide high specificity and sensitivity for long-term continuous monitoring of blood glucose concentration.
authors.affiliation: Department of Biomedical Engineering, University of Houston, Houston, TX 77204 USA.
authors.forename: Shang
authors.initials: S
authors.lastname: Wang
authors.affiliation: Department of Electrical and Computer Engineering, University of Houston, Houston, TX 77204 USA.
authors.forename: Tim
authors.initials: T
authors.lastname: Sherlock
authors.affiliation: Department of Biomedical Engineering, University of Houston, Houston, TX 77204 USA.
authors.forename: Betsy
authors.initials: B
authors.lastname: Salazar
authors.affiliation: Department of Biomedical Engineering, University of Houston, Houston, TX 77204 USA.
authors.forename: Narendran
authors.initials: N
authors.lastname: Sudheendran
authors.affiliation: Department of Mechanical Engineering, University of Houston, Houston, TX 77204 USA. He is now with Bioptigen Inc., Morrisville, NC 27560 USA.
authors.forename: Ravi Kiran
authors.initials: RK
authors.lastname: Manapuram
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Houston, TX 77204 USA.
authors.forename: Katerina
authors.initials: K
authors.lastname: Kourentzi
authors.affiliation: Department of Electrical and Computer Engineering, University of Houston, Houston, TX 77204 USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Ruchhoeft
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Houston, TX 77204 USA, and also with the Methodist Hospital Research Institute, Houston, TX 77031 USA.
authors.forename: Richard C
authors.initials: RC
authors.lastname: Willson
authors.affiliation: Department of Biomedical Engineering, University of Houston, Houston, TX 77204 USA, and also with the Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030 USA.
authors.forename: Kirill V
authors.initials: KV
authors.lastname: Larin
keywords: Biomedical monitoring; magnetic microparticles; optical coherence tomography; retroreflection; skin