Hand-held Photometer Based on Liquid-Core Waveguide Absorption Detection for Nanoliter-scale Samples

Abstract

This paper reports a fully integrated hand-held photometer based on the liquid-core waveguide (LCW) detection principle for nanoliter-scale samples. All components of the photometer including light-emitting diode (LED) light source, LCW flow cell, photodiode detector, dropper pump, electronic circuit, liquid-crystal display screen, and battery were fully integrated into a small-sized (12 x 4.5 x 2.1 cm) instrument. A bent optical coupler was developed to conduct the detection light into or out of the LCW flow cell through its sidewall. This design allowed the sampling probe, input and output optical couplers, and LCW flow cell to be integrated in a single Teflon AF capillary, which significantly simplified system structure, improved working reliability, and reduced sample consumption. Two UV-LEDs were used as light source in the photometer to achieve dual wavelength detection at 260 and 280 nm, which was applied to assess on-site the quality and quantity of DNA samples. The effective optical path length of the photometer was approximately 15 mm with a sample consumption of only 350 nL. The potential of the photometer applied in point of care testing was also demonstrated in the measurement of total cholesterol in serum samples.

Highly sensitive detection of thrombin using metal-waveguide-capillary based photometer and gold nanorods probe

“…As shown in Fig. 7 A few groups reported several aptamer-based sandwich assays for thrombin by applying various detection methods like electrochemistry, ECL, surface plasmon resonance and fluorescence [23][24][25][26][27][28]. This present work showed the MWC-based photometer has comparable sensitivity with the literatures.…”

RETRACTED ARTICLE: A compact photometer based on metal-waveguide-capillary: application to detecting glucose of nanomolar concentration

“…Currently, there are mainly two kinds of LWC, i.e., Teflon AF capillary (whose refractive-index is only ~1.3 and less than that of water), silica capillary coated with Teflon AF or metal films 1 3 4 . The low refractive-index material and large light incident-angle are required for realizing TIR at interface of dielectric materials 3 6 10 . As for Teflon AF capillary, Teflon AF is permeable to gas and could absorb little species in aqueous sample, due to its porous structure 3 11 .…”

Microfluidic Chips for Point‐of‐Care Immunodiagnostics

“…Considering peripheral equipment, a number of portable readers to measure signal from microfl uidic devices have been developed. [296][297][298] These readers include electronics for detection, signal processing, and signal transmission that operate on battery power. Important metrics for these electronics components are high performance with low power consumption.…”