This document describes a noninvasive wireless near infrared spectroscopy (NIRS) device for monitoring bladder filling capacity. The device uses the absorption properties of urine in the near infrared light spectrum to detect changes in bladder content. It consists of an LED light source, photodiode detector, filters, microcontroller, battery, and memory storage. In vitro and in vivo tests show it can differentiate between an empty and full bladder by detecting the abrupt decrease in light intensity when urine rises into the sensor's field. The aim is to help patients monitor their bladder without invasive methods to prevent health issues like renal damage.

1. Noninvasive Optical Monitoring of Bladder
Filling to Capacity Using a Wireless Near
Infrared Spectroscopy Device
K.KEERTHI
11211A1108
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2. CONTENTS
• Abstract
• Introduction
• NIRS device-Methodology
• Sensor block diagram
• Invitro setup
• Invivo setup
• Limitations
• Conclusion
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3. ABSTRACT
• Lack of bladder fullness sensation is an issue that arises in
different neurogenic conditions and in addition to influencing
patients’ quality of life, can result in serious kidney damage.
• We describe a wireless wearable sensor for detecting bladder
fullness using near infrared spectroscopy (NIRS).
• Capable of detecting changes in bladder content noninvasively.
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4. INTRODUCTION
(a) Evolution:
• NIRS is a technique increasingly used in NICUs to monitor
cerebral (or peripheral) tissue oxygenation and to tailor
haemodynamic and respiratory support.
• Recently NIRS device is used to study the haemodynamics
and oxygenation of bladder and used to evaluate bladder
function in health and disease.
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5. (b) Bladder Pathology
• Incontinence:
It is the inability to hold urine in the bladder because voluntary
control over the urinary sphincter is either lost or weakened.
• Enuresis:
It refers to a repeated inability to control urination particularly
tourette's syndrome in children.
• Urinary retention:
It is also known as ischuria, is an inability to completely
empty the bladder.
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6. (c)Techniques:
• Ultrasonic Scanning:
This technique uses ultrasonic imaging to differentiate the
urinary bladder from surrounding tissues and organs, produce
volume information, and estimate urine level.
• Bioelectrical impedance analysis:
This technique is principally used for determining extracellular
and total body water, for the changes in electrical impedance
used for detection of urine volume to be measured
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7. NIRS device-Methodology
• This method employs the absorption properties of human
tissue and water in the near infrared (NIR) light wavelength
range to measure changes in water content in the field beneath
a NIRS device.
• When the bladder rises into the NIR light field as it fills, the
water in the urine it contains results in high light absorption
that generates an abrupt decrease in the light intensity sensed
returning to the NIRS device.
• This event can be set to activate an alarm.
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9. Sensor Block Diagram
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10.  Source led:
• It is a 950 nm LED.
• Driven by a constant current driver, that in turn is controlled by a hardware
timer.
 Light detector:
• It is a 5.22 mmsq silicon photodiode.
• Integrated with a trans.-impedance amplifier.
 Filter:
• Active twin-T notch filter is used.
• Center frequency at 60 Hz
 Micro-controller:
• 16-bit low power microcontroller(MSP430F2274 Texas Instruments, TX,USA)
• Running at 16MHz.
• The filter’s output is sampled by a 10-bit analog to digital converter (ADC)
integrated on the MCU.
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11. Battery:
• The sensor is powered by a 3.7 V, 850 mAh lithium-ion
polymer rechargeable battery.
• Provides up to 20 hours of continuous monitoring.
USB connection
Memory storage:
• The sensor can log data on the 16 KB onboard flash memory
storage.
• The data can be later downloaded into a PC for further
analysis.
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12. IN-VITRO SETUP
• The setup was made to simulate the bladder,
urine and the abdominal tissue during bladder
filling and voiding.
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13. IN-VIVO SETUP
• The sensor is capable of differentiating
between full and empty bladder.
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14. LIMITATIONS
• Fat tissue layer under the optical opcode
location for bladder.
• Output drifts due to slight temperature
changes.
• Signal attenuation due to systemic
interferences.
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15. CONCLUSION
• A compact wireless optical sensor prototype is designed for
continuous noninvasive monitoring of the bladder in patients
who are unable to sense when their bladder is full.
• The device is capable of differentiating between when the
bladder is empty or contains a small volume of urine and
when it becomes full, by using the absorption properties of
water at a wavelength of 950 nm.
• This would potentially enable patients at risk for urinary
retention to protect themselves from renal damage, elderly
subjects prone to incontinence to retain the ability to void
voluntarily, and children with problematic enuresis to become
conditioned to when they need to wake to void.
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16. REFERENCES
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infrared spectroscopy,” Biomed. Spectrosc. Imag., vol. 1, no. 3, pp. 205–222, 2012.
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bladder: New parameters for evaluating voiding dysfunction,” Int. J. Spectrosc., vol. 2011, pp.
1–8, 2011.
• A. Macnab, B. Friedman, B. Shadgan, and L. Stothers, “Bladder anatomy physiology and
pathophysiology: Elements that suit near infrared spectroscopic evaluation of voiding
dysfunction,” Biomed. Spectrosc. Imag., vol. 1, no. 3, pp. 223–235, 2012.
• C. H. vander Vaart, J. R. J. de Leeuw, J. P. W. R. Roovers, and A. P. M. Heintz, “The effect of
urinary incontinence and overactive bladder symptoms on quality of life in young women,”
BJU Int., vol. 90, no. 6, pp. 544–549, Oct. 2002.
• S. Vaidyanathan, G. Singh, B. M. Soni, P. L. Hughes, K. F. Parsons, and P. Sett,
“Vesicoureteral reflux and bladder management in spinal cord injury patients.,” Spinal Cord,
vol. 40, no. 3, pp. 150–152, Mar. 2002.
• P. Petrican and M. A. Sawan, “Design of a miniaturized ultrasonic bladder volume monitor
and subsequent preliminary evaluation on 41 enuretic patients.,” IEEE Trans. Rehabil. Eng.,
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