A low-cost optical sensing device based on paired emitter-detector light emitting diodes

King Tong Lau; Susan Baldwin; Martina O'Toole; Roderick Shepherd; William J. Yerazunis; Shinichi Izuo; Satoshi Ueyama; Dermot Diamond

doi:10.1016/j.aca.2005.10.046

A low-cost optical sensing device based on paired emitter-detector light emitting diodes

King Tong Lau^*, Susan Baldwin, Martina O'Toole, Roderick Shepherd, William J. Yerazunis, Shinichi Izuo, Satoshi Ueyama, Dermot Diamond

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

78 Citations (Scopus)

Abstract

A low-power, high sensitivity, very low-cost light emitting diode (LED)-based device for intensity-based light measurements is described. In this approach, a reverse-biased LED functioning as a photodiode is coupled with a second LED configured in conventional emission mode. A simple timer circuit measures how long (in microsecond) it takes for the photocurrent generated on the detector LED to discharge its capacitance from logic 1 (+5 V) to logic 0 (+1.7 V). The entire instrument provides an inherently digital output of light intensity measurements for a few cents. This light intensity dependent discharge process has been applied to measuring concentrations of coloured solutions and a mathematical model developed based on the Beer-Lambert Law.

Original language	English
Pages (from-to)	111-116
Number of pages	6
Journal	Analytica Chimica Acta
Volume	557
Issue number	1-2
DOIs	https://doi.org/10.1016/j.aca.2005.10.046
Publication status	Published - 31 Jan 2006
Externally published	Yes

Keywords

Colorimetry
Light emitting diode
Optical sensor
Photodiode
Sensor networks

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10.1016/j.aca.2005.10.046

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title = "A low-cost optical sensing device based on paired emitter-detector light emitting diodes",

abstract = "A low-power, high sensitivity, very low-cost light emitting diode (LED)-based device for intensity-based light measurements is described. In this approach, a reverse-biased LED functioning as a photodiode is coupled with a second LED configured in conventional emission mode. A simple timer circuit measures how long (in microsecond) it takes for the photocurrent generated on the detector LED to discharge its capacitance from logic 1 (+5 V) to logic 0 (+1.7 V). The entire instrument provides an inherently digital output of light intensity measurements for a few cents. This light intensity dependent discharge process has been applied to measuring concentrations of coloured solutions and a mathematical model developed based on the Beer-Lambert Law.",

keywords = "Colorimetry, Light emitting diode, Optical sensor, Photodiode, Sensor networks",

author = "Lau, {King Tong} and Susan Baldwin and Martina O'Toole and Roderick Shepherd and Yerazunis, {William J.} and Shinichi Izuo and Satoshi Ueyama and Dermot Diamond",

note = "Funding Information: The authors wish to thank Science Foundation Ireland SFI for grant support under the Adaptive Information Cluster Award (SFI 03/IN3/1361).",

year = "2006",

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doi = "10.1016/j.aca.2005.10.046",

language = "English",

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journal = "Analytica Chimica Acta",

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AU - Lau, King Tong

AU - Baldwin, Susan

AU - O'Toole, Martina

AU - Shepherd, Roderick

AU - Yerazunis, William J.

AU - Izuo, Shinichi

AU - Ueyama, Satoshi

AU - Diamond, Dermot

N1 - Funding Information: The authors wish to thank Science Foundation Ireland SFI for grant support under the Adaptive Information Cluster Award (SFI 03/IN3/1361).

PY - 2006/1/31

Y1 - 2006/1/31

N2 - A low-power, high sensitivity, very low-cost light emitting diode (LED)-based device for intensity-based light measurements is described. In this approach, a reverse-biased LED functioning as a photodiode is coupled with a second LED configured in conventional emission mode. A simple timer circuit measures how long (in microsecond) it takes for the photocurrent generated on the detector LED to discharge its capacitance from logic 1 (+5 V) to logic 0 (+1.7 V). The entire instrument provides an inherently digital output of light intensity measurements for a few cents. This light intensity dependent discharge process has been applied to measuring concentrations of coloured solutions and a mathematical model developed based on the Beer-Lambert Law.

AB - A low-power, high sensitivity, very low-cost light emitting diode (LED)-based device for intensity-based light measurements is described. In this approach, a reverse-biased LED functioning as a photodiode is coupled with a second LED configured in conventional emission mode. A simple timer circuit measures how long (in microsecond) it takes for the photocurrent generated on the detector LED to discharge its capacitance from logic 1 (+5 V) to logic 0 (+1.7 V). The entire instrument provides an inherently digital output of light intensity measurements for a few cents. This light intensity dependent discharge process has been applied to measuring concentrations of coloured solutions and a mathematical model developed based on the Beer-Lambert Law.

KW - Colorimetry

KW - Light emitting diode

KW - Optical sensor

KW - Photodiode

KW - Sensor networks

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JF - Analytica Chimica Acta

IS - 1-2

ER -

A low-cost optical sensing device based on paired emitter-detector light emitting diodes

Abstract

Keywords

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