Detecting Sleep Apnea with theTI MSP430 Microcontroller

Aaron Sander & Ramzie Fathy

Mentor: Sakib Hasan

CURENT YSP

Final Presentation

Tuesday July 16th, 2014

Knoxville, Tennessee

Our Objective

Sleep Apnea is very common in young infants who have an underdeveloped nervous system.

Our research was based around finding a system which could analyze breathing signals in various situations and alert caretakers if apnea sets in.

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OUTLINE

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• What is Sleep Apnea?

• What is a Microcontroller?

• TI MSP430

• Results

What is Sleep Apnea?

• Apnea literally means “cessation of breathing”

• Definition is a lack of breathing for as low as 20 seconds up to 2 minutes for adults, may happen nearly 100 times a night

• Three majors forms of Sleep Apnea

Obstructive Sleep Apnea (most common)

- when airway is physically blocked by tongue, tonsils, etc.

Central Sleep Apnea (20% of cases)

- when brain forgets to tell body to breathe, especially common in infants with undeveloped nervous system

Mixed Sleep Apnea

- combination of the two

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Central Sleep Apnea

• Breathing regulated by Pre-Bötzinger Complex which may not be developed yet in young children

• Can be common in people who have Parkinson’s, Alzheimer’s, or have had a stroke or brain injury

• Located in Medulla Oblongata (brainstem)

• Oxygen level in body can drop to life-threatening levels (hypoxemia)

• Inversely, the CO2 levels in the blood can increase to an unsafe level (hypercapnia)

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Apnea – Hyperventilation - Apnea

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Cheynes-Stokes Respiration

The Microcontroller

• The Microcontroller is a small computer on a single integrated circuit containing a processor core, memory, and programmable input/output peripherals.

• Programmed in different programming languages

• Capabilities include pH sensor, temperature indicator

• Many Applications

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MSP430

• A mixed-signal microcontroller family from Texas Instruments.

• Capabilities include temperature indicator, Red/Green LEDs, and Micro-USB port.

• Programmed in C.

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Results

• Created a program using the MSP430

• Written in C on Code Composer Studio

• Piezoelectric Transducer is used to convert pressure (breath) to electrical signal

• Program analyzes this to determine if a child is properly breathing

• Threshold can be modified on case by case basis

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Actual Code

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Pseudo-Code

Clock On

Timer On

Green LED On

Analog-Digital Converter On

Threshold determined

If (voltage >= threshold)

Timer resets to 0

If (voltage < threshold)

Clock continues counting

Loop

When clock count = 10, Red LED will indicate apnea

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Testing the Program

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References

• MSP430 User Guides and Datasheets

• http://electronics.howstuffworks.com/microcontroller.htm

• http://www.nhlbi.nih.gov/health/health-topics/topics/sleepapnea/

• http://sleepfoundation.org/sleep-disorders-problems/sleep-apnea

• Rybak IA, Abdala AP, Markin SN, Paton JF, Smith JC (2007). "Spatial organization and state-dependent mechanisms for respiratory rhythm and pattern generation". Progress in Brain Research. Progress in Brain Research 165: 201–20

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Acknowledgements

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Sakib Hasan

CURENT Program

National Science Foundation