Optical image sensors and their application in radon detection

Griffin, Ryan H.; Tarr, N. G.

doi:10.1117/12.2033635

Cited by 4 publications

(11 citation statements)

References 3 publications

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“…A solution for radon detection using silicon diodes was developed at Carleton University by R.H. Griffin and discussed in [4,5,[19][20][21][22][23]. This monitor used an IC containing an array of pn diodes to detect alpha particle radiation from radon progeny.…”

Section: Alpha Particle-detecting Mos Integrated Circuitmentioning

confidence: 99%

“…Electrostatics was used to concentrate charged radon progeny, polonium-218, onto the surface of the IC [24]. The electrostatic concentrator (EC) was built from a polyethylene funnel where the inside was metalized using 32 µm thick copper tape [22]. The copper tape was separated into two sections to create a stronger sweep field inside the cone.…”

Section: Alpha Particle-detecting Mos Integrated Circuitmentioning

confidence: 99%

“…The top of the cone was covered by copper mesh which was attached to the top electrode as shown in Figure 2.7. The electrostatic concentrator used has a 243 mL capacity with a top and bottom diameter of 21 mm and 104 mm respectively [22]. Since the bottom diameter of the electrostatic concentrator was significantly larger than the IC, it will produce a homogeneous radon progeny distribution across the entire IC.…”

Section: Alpha Particle-detecting Mos Integrated Circuitmentioning

confidence: 99%

“…This makes the radon monitor less sensitive, since not all the radon progeny is concentrated onto the IC. A potential of 1000 V and 800 V was applied to the top and bottom electrode respectively [22]. To create this high voltage, a 50 stage Cockcroft-Walton charge pump from [22] shown in Figure 2.8, was used to convert a 15 V peak-to-peak square wave from a LM555 timer into the DC voltages.…”

Section: Alpha Particle-detecting Mos Integrated Circuitmentioning

confidence: 99%

“…The CMOS alpha particle-detecting IC was designed following an approach similar to that used for the MOS IC in [4,5,[19][20][21][22][23]. The alpha particle sensitive silicon diodes, or sense diodes, are structured in a 16×16 array as shown in Figure 3.1.…”

Section: Cmos Icmentioning

confidence: 99%

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Radon Detection Using CMOS Alpha Sensor

Ross¹

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A radon monitor based on a 3 mm×3 mm alpha particle-detecting IC fabricated in a foundry CMOS process is reported. The alpha-detecting IC consists of a 16×16 array of pn junction diodes (sense diodes) that are precharged in reverse bias and then allowed to electrically float. Radon progeny are collected on the IC using an electrostatic concentrator. On-chip comparators detect the voltage change induced in a sense diode by an alpha particle emission from radon progeny passing though a sense diode. The comparator outputs are monitored by a microcontroller which processes the data and transmits it to a microcomputer using Bluetooth. The monitor has a sensitivity of 1.12 counts per hour per 100 Bq/m 3 of radon activity. The monitor appears suitable for mass production at very low cost.ii Acknowledgments I would like to thank N. Mikhail and S. Follows for their assistance in providing equipment and assistance in testing the alpha-detecting CMOS IC and radon monitor.The contribution of the many students who designed and tested earlier versions of the radon monitors is also gratefully acknowledged. Lastly, I would like to thank Dr. N.Garry Tarr and Dr. Ryan H. Griffin for their supervision and guidance throughout my involvement in this research.iii to the sense bit line of the alpha particle-detecting CMOS IC. V refVoltage of the reference diode. xii V ref BlVoltage of the reference bit line.V sense Voltage of the sense diode.V senseBl Voltage of the sense bit line.V strike Voltage change in a sense diode due to an alpha particle strike (theoretically 250 mV). V switchThe input voltage where the analog comparator's output voltage is 50% of logic High voltage.xiii Chapter 1

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Section: Alpha Particle-detecting Mos Integrated Circuitmentioning

confidence: 99%

Section: Alpha Particle-detecting Mos Integrated Circuitmentioning

confidence: 99%

Section: Alpha Particle-detecting Mos Integrated Circuitmentioning

confidence: 99%

Section: Alpha Particle-detecting Mos Integrated Circuitmentioning

confidence: 99%

Section: Cmos Icmentioning

confidence: 99%

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Radon Detection Using CMOS Alpha Sensor

Ross¹

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Screen printed electrostatic concentrator with origami-inspired design for low-cost radon detection

Hyland

Graddage

Griffin

2019

Flex. Print. Electron.

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There is an increasing awareness of the dangers posed by elevated radon concentration in indoor spaces. This has led to demand for improved measurement solutions which enable low-cost, accurate, and practical measurement of radon concentration. In this work, the use of screen printing to fabricate an electrostatic concentrator for radon detection is demonstrated. An origami-inspired design enables the use of printed electronics as a manufacturing technology with a resulting reduction in component cost and weight. A new metric for such electrostatic concentrators known as the 'active volume' was defined, taking into account the time of flight to the sensor and residence time of the radon progeny. This metric was utilised in a genetic algorithm in order to optimise the concentrator design, resulting in a 62% improvement in radon progeny concentration, enabling more rapid and accurate understanding of radon risk.

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