Optical instrument design for interrogation of dermally-implanted luminescent microparticle sensors

Abstract

Luminescence-based sensors have been developed in microparticle formats for biochemical targets such as glucose, enabling use of dermal implants for on-demand monitoring. For these to be deployed and interrogated in vivo, a matched optoelectronic system for delivery of excitation, collection and analysis of luminescence response is needed. In this work, simulations based on Monte Carlo ray-tracing were performed for models of luminescent microparticle materials embedded in skin. The spectral and spatial distribution of luminescence escaping the skin was determined for different concentrations, implantation depths, and input beam sizes. Results indicate that the implant environment does not significantly alter the measured spectral intensity ratios. The escaping emission light possesses measurable power and spectral information for quantitative analysis. Using these findings, an optical system has been designed specifically for sensor interrogation and response acquisition, and is currently implemented in hardware. Following benchtop validation and signal-to-noise maximization with tissue phantoms, the instrument will be used for measurement on sensors in rat subjects.

Glucose Response of Near-Infrared Alginate-Based Microsphere Sensors Under Dynamic Reversible Conditions

“…[13][14][15] Such implants may be interrogated noninvasively using simple optical instrumentation. [16][17][18][19] Towards this goal, several platform technologies have been established using different microsphere and microcapsule materials as well as different transduction approaches. [6][7][8][9][10][11][12] Our specific team efforts have focused on use of alginate microparticles with competitive binding sensing chemistry, and we recently reported on the response of fluorescent dissolved-core alginate microsphere glucose sensors using visible dyes.…”

Smart tattoo: technology for monitoring blood glucose in the future

“…The smart tattoo consists of an intradermally embedded array of biosensors that are exposed to interstitial fluid, enabling the measurement of local changes in glucose, which correlate with blood glucose levels (Caplin et al, 2003 [AQ16 v old ref, please update]). The implant emits visible colour changes corresponding to the glucose levels in the bloodstream, which in turn can be interrogated non-invasively through the skin using a simple optical device ( Figure 2) (Long et al, 2008).…”

High-throughput spectral system for interrogation of dermally-implanted luminescent sensors

“…Following the standard spectrometer design, Figure 3(a) shows the scheme of the system integrating the functions of excitation delivery, luminescence collection and spectrum measurement. Part I is the optical system to deliver excitation and collect emission light designed in previous work [16]. Part II is the layout of the customized spectrometer.…”