An In-Situ Highly Sensitive and Reliable Chlorophyll Sensor Based on Pseudo-Random Sequence Modulation

A highly sensitive and reliable chlorophyll sensor is proposed and evaluated to meet the demand of in-situ chlorophyll detection. As the major innovation, pseudo-random sequence modulation is introduced into the amplitude measurement of the fluorescence for the first time. Compared with the conventional single frequency square wave modulation, the pseudo-random sequence modulation could spread the spectrum of the fluorescence, and improve the sensitivity and the interference suppression ability of the sensor without increasing the complexity of the system's hardware. The sensitivity experiments show that the sensor could detect chlorophyll as low as 0.0103 μg/L, with the concentration range of 0~25 μg/L and the R-square of 0.9998. In the interference suppression test, for the same interference in the passing band, the maximum response of the 31 bits PRS modulation system is 2.3 times smaller than that of the single frequency square wave modulation system.

[1]  E. Sertel,et al.  Determination of chlorophyll-a amount in Golden Horn, Istanbul, Turkey using IKONOS and in situ data , 2009, Environmental monitoring and assessment.

[2]  F. MacWilliams,et al.  Pseudo-random sequences and arrays , 1976, Proceedings of the IEEE.

[3]  Yajun Ha,et al.  Pseudo-random single photon counting for time-resolved optical measurement. , 2008, Optics express.

[4]  R. Challis,et al.  Sub-threshold sampling in a correlation-based ultrasonic spectrometer , 2011 .

[5]  P. Horton,et al.  Studies on the induction of chlorophyll fluorescence in barley protoplasts. II. Resolution of fluorescence quenching by redox state and the transthylakoid pH gradient , 1984, Proceedings of the Royal Society of London. Series B. Biological Sciences.

[6]  Rudolf Zetik,et al.  Liquid and moisture sensing by ultra-wideband pseudo-noise sequence signals , 2007 .

[7]  Murray Hodgson,et al.  Use of pseudo-random sequences and a single microphone to measure surface impedance at oblique incidence , 1997 .

[8]  Yves Rolain,et al.  Design and characterization of an RF pulse train generator for large-signal analysis , 2009 .

[9]  J. Brezmes,et al.  Quantitative gas mixture analysis using temperature-modulated micro-hotplate gas sensors: Selection and validation of the optimal modulating frequencies , 2007 .

[10]  M. Conkright,et al.  Comparison of global chlorophyll climatologies: In situ, CZCS, Blended in situ -CZCS and SeaWiFS , 2003 .

[11]  Chang-Soo Park,et al.  A Wide Dynamics and Fast Scan Interrogating Method for a Fiber Bragg Grating Sensor Network Implemented Using Code Division Multiple Access , 2012, Sensors.

[12]  Anders la Cow-Harbo.  Using Spread Spectrum Transform for Fast and Robust Simultaneous Measurement in Active Sensors with Multiple Emitters , 2004 .

[13]  J. Brezmes,et al.  Optimised temperature modulation of metal oxide micro-hotplate gas sensors through multilevel pseudo random sequences , 2005 .

[14]  K Maxwell,et al.  Chlorophyll fluorescence--a practical guide. , 2000, Journal of experimental botany.

[15]  Akiko Hirai,et al.  White-light interferometry using pseudo random-modulation for high-sensitivity and high-selectivity measurements , 1999 .

[16]  Peter Alfred Payne,et al.  Pseudo-random binary sequence interrogation technique for gas sensors , 1998 .

[17]  Hamid Hemmati,et al.  Sub-millimeter laser ranging results using a pseudo-random code modulation , 2005, SPIE LASE.

[18]  Hangen He,et al.  Novel Ultrasonic Ranging Approach Based on Spread Spectrum Modulation , 2006, 2006 International Conference on Communication Technology.

[19]  R. Nowak,et al.  Laser ceilometer with pseudo random code modulation for cloud high measurements , 2001, Systems of Optical Security.

[20]  N. Chen,et al.  Time-resolved optical measurements with spread spectrum excitation. , 2002, Optics letters.

[21]  Roland Müller,et al.  Acoustic tomography on the basis of travel-time measurement , 2004 .

[22]  M. Barták,et al.  Technique of the Modulated Chlorophyll Fluorescence: Basic Concepts, Useful Parameters, and Some Applications , 1999, Photosynthetica.

[23]  V. Mitev,et al.  Pseudo-random noise-continuous-wave laser radar for surface and cloud measurements , 2005 .

[24]  S. Na,et al.  Impedance-based non-destructive evaluation of the FRP adhesive joints in corrosive environment with re-usable technique , 2011, Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring.