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Development of Mobile Radiation Monitoring System Utilizing Smartphone and its Field Test in Fukushima

Development of Mobile Radiation Monitoring System Utilizing Smartphone and its Field Test in Fukushima. Speaker : Li-Wei Wu Advisor: Dr. Kai-Wei Ke 2013/10/14. Outline. Introduction What is Radiation Hardware design Software design Field testing Conclusion Reference. Introduction.

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Development of Mobile Radiation Monitoring System Utilizing Smartphone and its Field Test in Fukushima

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  1. Development of Mobile Radiation Monitoring System Utilizing Smartphone and its Field Test in Fukushima Speaker: Li-Wei Wu Advisor: Dr. Kai-Wei Ke 2013/10/14

  2. Outline • Introduction • What is Radiation • Hardware design • Software design • Field testing • Conclusion • Reference

  3. Introduction • The Daiichi Nuclear Power Plant accidents in Fukushima have stimulated desire of ordinary people to own radiation sensors. • March 16, 2011, the SAFECAST team started data collection of air dose-rates using mobile sensors. • Conventional radiation sensinginstrumentsare too expensive for members of the general public,as well as being difficult to obtain and use.

  4. Introduction • Radiation-watch.orgThis is an open-source and non-profit projectinvolving a number of volunteer engineers and scientists. we initially released a unique radiationdetector named Pocket Geiger(POKEGA) in August 2011, designedto be connected to a smartphone. • In order to reduce costs while maintaining accuracy andflexibility, they used a combination of a PIN photodiodedetector and a smartphone connected via a microphonecable.

  5. What is Radiation? • 輻射是一種具有能量的波或粒子。 • 無線電波、微波、可見光、X射線、ϒ射線等、超音波，以及從放射性物質發射出來的微小粒子(如α粒子、β粒子、中子等)

  6. Hardware design • 充氣式偵檢器 • 閃爍偵檢器 • 半導體偵檢器

  7. Hardware design – Type 1 • The first model of the POKEGA series, was marketed in an unfinished, easy-to-assemble kit-style package in order to facilitate rapid development and cost reductions. • The output pulse from a photodiode is quite low and narrow, while the input gain and sampling rate of a smartphone are extremely low and slow. • Charge amplifier optimized the narrow radiation pulses, so it can be detected using the low sampling rate of the smartphone audio circuit.

  8. Hardware design – Type 1 • The input gain and frequency characteristics of the analog-to-digital (A/D) circuits vary somewhat depending on the model or generation of the smartphone. • Application software discriminates radiation pulses from background noise by means of thresholds.

  9. Hardware design – Type 1 n = αr α : conversion factor r : dose rate [μSv/h] n : count rate [cpm] α

  10. Hardware design – Type 1

  11. Hardware design – Type 2 • The Type 2 model was designed to power from the smartphone. • They have implemented an internal voltage-generation circuit that uses an earphone stereo tone generated by the application software. • In order to prevent hearing damage in situations where users accidentally connect headphones to the smartphone while the POKEGA application is running, the signal frequency was set at 20 kHz, which is just above audio frequency for human.

  12. Hardware design – Type 2 整流 濾波 脈動直流

  13. Hardware design – Type 2

  14. Hardware design – Type 3 • The Type 3 device has a comparator circuit and digitaloutput for radiation pulses along with a pull-up resistor thatallows it to be connected to various smartphones. • Type 3 device equipped with a noise-detection circuit because, PIN diodes are susceptible to noise vibrations. There are two thresholds in the circuit; one is used to detectradiation pulses, while the other is used to detect the noisevibrations

  15. Hardware design – Type 3

  16. Hardware design – Type 3

  17. Hardware design – Type 4 • The Type 4 device was developed to reduce measurementtime. • The Type 4 device uses a large-area X 100-7 PIN photodiode.

  18. Hardware design – Type 5 • It was designedfor remote sensing using embedded microcontrollers.

  19. Software design • The software is designed to visualize radiation measurements.

  20. Software design

  21. Field testing

  22. Field testing

  23. Conclusion There are now approximately 12,000 POKEGA users andmore than 1 million datahavebeen collected from them. Currently, about 1,800 people havesubscribed to the Facebook group, where they have postedthousands of comments. That group was primarily created tosupport users, the majority of the topics relateto sharing dose rate reports in various areas, as well as followupsby nearby inhabitants or radiation specialists. Suchinteractions have contributed to improving radiation literacy ofthe general publicand POKEGA’s hardware and software.

  24. Reference • Yang Ishigaki, Yoshinori Matsumoto, Ryo Ichimiya, and Kenji Tanaka, “Development of Mobile Radiation Monitoring System Utilizing Smartphone and Its Field Tests in Fukushima” Sensors Journal, Oct. 2013 IEEE • http://www.radiation-watch.org/

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