A Colorimetric CMOS-Based Platform for Rapid Total Serum Cholesterol Quantification

Mohammed A Al-Rawhani,Chunxiao Hu,Boon Chong Cheah,Alasdair Iain Macdonald,Michael P Barrett,Christopher Martin,James Beeley,Gordon Campbell,James P Grant,Luiz Carlos Gouveia,David R S Cumming

doi:10.1109/jsen.2016.2629018

Abstract

Elevated cholesterol levels are associated with a greater risk of developing cardiovascular disease and other illnesses, making it a prime candidate for detection on a disposable biosensor for rapid point of care diagnostics. One of the methods to quantify cholesterol levels in human blood serum uses an optically mediated enzyme assay and a bench top spectrophotometer. The bulkiness and power hungry nature of the equipment limits its usage to laboratories. Here, we present a new disposable sensing platform that is based on a complementary metal oxide semiconductor process for total cholesterol quantification in pure blood serum. The platform that we implemented comprises readily mass-manufacturable components that exploit the colorimetric changes of cholesterol oxidase and cholesterol esterase reactions. We have shown that our quantification results are comparable to that obtained by a bench top spectrophotometer. Using the implemented device, we have measured cholesterol concentration in human blood serum as low as 29 $\mu \text{M}$ with a limit of detection at 13 $\mu \text{M}$ , which is approximately 400 times lower than average physiological range, implying that our device also has the potential to be used for applications that require greater sensitivity.

Highlights

P OINT of care diagnostics are transforming the healthcare industry, by facilitating the use of home-testing to provide an early indication of potential illness and disease [1]–[3]
It can be seen that there is an overlap between sensitivity of the photodiode and the absorbance spectrum of the enzyme assay, around 500 nm
An off-the-shelf commercial green light emitting diode (LED) was measured using the same spectrometer and is shown to have a peak at 505 nm, which was well positioned at the overlap of the two traces

Summary

Introduction

P OINT of care diagnostics are transforming the healthcare industry, by facilitating the use of home-testing to provide an early indication of potential illness and disease [1]–[3]. The development of low-cost and effective consumable biosensors [4], [5] is at the forefront of the research for userorientated testing, driven in part by the need for rapid diagnosis and monitoring without overburdening the resources of the healthcare services. Date of publication November 15, 2016; date of current version December 20, 2016. The associate editor coordinating the review of this paper and approving it for publication was Prof.

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Conclusion