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16.541 INTRODUCTION TO BIOSENSORS
University of Massachusetts Lowell
The Department of
Electrical and Computer
Engineering
Subject:
Introduction to Biosensors
Wireless Optical Sensor Network
Project Report One
Team members: Ravi G Bhatia
Wenchan Tong
Aiken Pang
Report Submit Date: 21st March, 2007
16.541 INTRODUCTION TO BIOSENSORS
CONTENTS
Objectives ..........................................................3
Background.......................................................4
Methodology .....................................................7
Implementation ................................................8
Result .............................................................. 10
Challenges ...................................................... 12
Reference ........................................................ 13
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16.541 INTRODUCTION TO BIOSENSORS
Objectives
In the market, optical fiber biosensor needs to use bulky equipments that include
tunable laser and spectrum analyzer. The spectrum analyzer cans only analyzer
one to two optical fiber biosensor. If we have a lot of sample need to be analyze
at the same time. We need to use more equipment that is expensive. The target
samples need to be connected physically to the equipments. These wired
connection let the testing not flexible enough, when you testing the samples in a
lab which use a central computer to log and analyze all the samples data at the
same time.
In this project, we would want to provide a low cost wireless network for the
connection between optical fiber biosensor and central computer. It will include
three parts.
Wireless module: It include a microcontroller, Analog to Digital converter and
RF transmitter
Photo detector: It converts light intensity to electrical signal (Voltage)
Optical biosensor: It will reflect the laser which the intensity will affect by
number of biomaterials attachments.
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16.541 INTRODUCTION TO BIOSENSORS
1
Background
Optical Fiber BioSensor System
1.1 Review of Optical Fiber biosensor Theory (Field of study)
The biosensor Fabry-Pérot interferometer
1.2 Motivation of using wireless network in optical sensor system
We want to find a low cost, ease of deployment, multi-source sensor and battery
operation platform to transfer the data to central computer. Using wireless sensor
network is one of good solution.
1.3 Problem description
Using optical fiber as biosensor has grown popular over the past few years as
makers continue to develop new technology.
One of the problems of optical biosensor is that the sensor needs to wire with a
massive machine. This limitation make the sensor cannot be portable. Although
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16.541 INTRODUCTION TO BIOSENSORS
the technology have fast testing using optical biosensor, the time for transport the
sample and setup the testing is too long.
Another problem is that we need use more machines (increase the cost), if we
want to do more than one testing at the same time.
However, the demand of the market is increasing. Portable device is a trend for
sensor.
Therefore, it is important to create a portable, multi-sources, ease of setup
platform for optical biosensor
1.4 Optical sensor
Sensor Head is an optical cavity such as a Fabry Perot cavity. Biomolecular
interaction changes optical path length. Intensity change proportional to optical
path length and as the path length changes photodetector will detect change in
intensity and transmit that information through the wireless module.
Assumption:
Wavelength:
1550nm
Peak Output:
0.04mW
Valley:
0.004mW
Intensity Change: 1µW
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16.541 INTRODUCTION TO BIOSENSORS
1.5 Photo detector
The input of the photodetector is the laser reflected from the optical biosensor.
The intensity of the laser is proportional to the wavelength and the “L”. The “L” is
related to the number of biomaterials attached on the biosensor. From the about
assumption, we need to use InGaAs Avalanche Photodetector (APD).
1.6 Wireless sensor network
We select the wireless sensor network because the network itself is a mesh network.
Mesh network mean that it can auto construct the network connection. Each node in
the network can work as forwarder (help other node to forward their data to the PC).
Therefore, the sensor can be far away from the computer. In the network, it can be
more than one sensor and each node can also have more than one sensor.
Network coordinator
Full Function node
Reduced Function node
Communications flow
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16.541 INTRODUCTION TO BIOSENSORS
2
Methodology
For designing a wireless optical sensor network (WOSN) , there were three
predicaments.
Optical
Sensor
1.
Transform the laser intensity to voltage from optical sensor
2.
Digitize the voltage value to digital format
3.
Transmit the digital data from the remote site to PC
Photo Sensor
ADC
Microcontroler
MCU
Radio Frequency
Transmitter
Microcontroler
MCU
Radio Frequency
Transmitter
Analog data
PC
Digital data
For design of WOSN, this project comprises four stages.
First stage: “Selection of photo detector”
Second stage: “Simulation of optical sensor response”
Third stage: “Connect photo detector to the wireless network module”
Fourth stage “Modify PC program for display Intensity and detect changing ”
Fifth stage: “Testing the sensitivity of the ADC”
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16.541 INTRODUCTION TO BIOSENSORS
3
Implementation
3.1 Division of work
3.1.1 Ravi
Ravi will work on optical biosensor and photo sensor. He will find a correct
photo sensor depends on the need of the optical sensor. He will ready the
laser for the input to the biosensor.
3.1.2 Wenchan
Wenchan will modify the PC side software for display the correct value with
the unity of light intensity and the Analog to Digital converter.
3.1.3 Aiken
The wireless network will be ready by Aiken. He will programming the wireless
sensor node for correctly send the data back to PC.
3.2 Timetable
WEEK
TASK PLAN
March 21 - 25
Order InGaAs APD
March 26 - 31
Modify Wireless Sensor Algorithm for Voltage Calibration
April
2-7
Simulate Biosensor operation for obtaining intensity change
April
9 - 21
Hardware Assembly & Testing
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16.541 INTRODUCTION TO BIOSENSORS
3.2 Budge
Wireless sensor node: US$100 each (we need at least two)
Photosensor: US$50 each
Connector: US$10each (at least 4)
Total cost will be $290
3.3 Optical sensor simulation
We will use a connect optical fiber
equipment to simulate the situation of
attaching bio materials.
3.4 Software development
3.4. 1 Programming wireless sensor module
Now the module can be send the photosensor (one of the ADC in the module)
value back to PC.
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16.541 INTRODUCTION TO BIOSENSORS
5
Result
The purpose of the project is to construct wireless optical sensor network, which
is cost-effective and low power consumption.
5.1 Data from sensor node
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16.541 INTRODUCTION TO BIOSENSORS
5.2 Simulation of optical biosensor (OBS)
The left hand side is the output of the OBS under the simulation of no biomaterials attached on
the biosensor.
The right hand side is the output of the OBS under thesimulation of some biomaterials attached
on the biosensor.
We found that the output of the OBS would increase where there is some biomaterials attached
on the OBS.
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16.541 INTRODUCTION TO BIOSENSORS
6
Challenges
6.1 Difficulties encountered
1. 1550 nm wavelength Detection - InGaAs Avalanche Photodetector needed
2. Aligning sensor with photodetector – Need a photodetector with Fiber Pigtail
connector
3. Calibration of wireless sensor to convert intensity difference into appropriate
voltage for information processing
4. Cost and Compactness of our Design
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16.541 INTRODUCTION TO BIOSENSORS
8
Reference
1)
www.moteiv.com
2)
www.zigBee.org
3)
Fiber Optic Sensors, Francis Yu, Shizhuo Yin
4)
www.sales.hamamatsu.com
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