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Jan 23, 2023 472 likes •823 views

PhO 2 Smartphone based Blood Oxygen Level Measurement using Near-IR and RED Wave-guided Light Nam Bui, Anh Nguyen, Phuc Nguyen, Hoang Truong, Ashwin Ashok, Thang Dinh, Robin Deterding, Tam Vu 1/30 Chronic Obstructive Pulmonary Disease ( COPD )

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Smartphone based Blood Oxygen Level Measurement using Near-IR and RED Wave-guided Light

Nam Bui, Anh Nguyen, Phuc Nguyen, Hoang Truong, Ashwin Ashok, Thang Dinh, Robin Deterding, Tam Vu

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PhO2

SLIDE 2

Chronic Obstructive Pulmonary Disease (COPD)

24 Million Americans have COPD

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Leading cause of death in the US, 2016

OFTEN

FOUND IN LATE STAGE

$34,000 treatment in ICU Early detection of COPD is key to successful treatment

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Heart rate Blood pressure Breathing rate Wheezing sound Oxygen saturation (SpO2)

Vital signs screening in COPD

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Oxygen Saturation needs to be measured frequently

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Oxygen Saturation (SpO2)

𝑻𝒒𝟏𝟑 = 𝑶𝒑. 𝒑𝒚𝒛𝒉𝒇𝒐𝒃𝒖𝒇𝒆 𝒊𝒇𝒏𝒑𝒉𝒎𝒑𝒄𝒋𝒐 𝑼𝒑𝒖𝒃𝒎 𝑶𝒑. 𝒊𝒇𝒏𝒑𝒉𝒎𝒑𝒄𝒋𝒐 𝟐𝟏𝟏%

Oxygenated hemoglobin Deoxygenated hemoglobin

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Photon Detector

IR emitter Red emitter

R IR

Non-invasive Measurement of Oxygen Saturation

Intensity t Intensity t

ACIR ACR

𝑻𝒒𝟏𝟑 = 𝒈 𝑩𝑫𝑺 𝑩𝑫𝑱𝑺

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Red and IR Wavelength Selection

At Red= 660 nm and IR = 960 nm, the difference of light absorption by oxygenated hemoglobin and deoxygenated hemoglobin is largest.

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Absorbed by red pigmentation Harmful Low penetration

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Pros Cons

 High accuracy  Inconvenient  Costly

Smartphone-based blood oxygen measurement

Dedicated Hardware Solutions

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A solution to capture the oxygen level and is

High accuracy. Low-cost. Easy to make by patients

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SLIDE 9

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PhO2

Smartphone based Blood Oxygen Level Measurement

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IR emitter Red emitter

PULSE OXIMETER

Hardware Challenges

PHONE BASED PULSE OXIMETER

Light Source

SLIDE 11

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Challenge. Phone’s camera IR filter

Sensor

IR filter

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Existing Software-based Solutions

DigiDoc iHealthCare

R G B Color Image

Red Light IR Light

DISADVANTAGES  Inaccurate: Green channel is mostly absorbed by red pigmentation.  Coarse-grained: one record per 10 seconds.

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Solution.

Red and NIR for Oxygen Saturation Measurement

NIR

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NIR

is available in most of phone’s flashlight and is not filtered by the phone’s camera. has similar characteristics of hemoglobin absorption with the IR lights. NIR

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PhO2 NIR Extraction Technique

Absorbed by red pigmentation

Green filter

Absorbe d

NIR

Red and Green filter cuttoff

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And 5 More Challenges…

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Smartphone’s camera picks up most of the lights Finger movement and Contact pressure

Pressure Micro movements

RGB Intensity

Conversion between RGB and light intensity Flashlight heat can cause skin burn

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3D printed Optical Hardware Add-on

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Smartphone’s camera picks up most of the lights

RGB Intensity

Conversion between RGB and light intensity Finger movement and contact pressure

Pressure Micro movements

Flashlight can cause skin burn

3D printed Optical Hardware Add-on

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Wavelength selection 𝝁𝑺= 678 nm 𝝁𝑶𝑱𝑺= 724 nm

𝑻𝒒𝟏𝟑 = 𝜻𝑰𝒄 𝒔 − 𝜻𝑰𝒄 𝒔 𝑺 𝜻𝑰𝒄 𝒋𝒔 − 𝜻𝑰𝒄𝑷𝟑 𝒔 + 𝜻𝑰𝒄𝑷𝟑 𝒋𝒔 − 𝜻𝑰𝒄 𝒋𝒔 𝑺

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X:678 Y: 724 Z:1.002

𝜷

𝜷 = 𝒃𝒔𝒅𝒖𝒃𝒐(𝒃/𝒄)

a b

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Pressure Detection and Recommendation

Normalized Intensity

PPG signal in a 7 seconds window

Sample Normalized Intensity Sample

PPG signal in a 7 seconds window 21/30

Normalized Intensity

PPG signal in a 7 seconds window

Sample

SLIDE 20

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Heat Reduction with Distributed Lighting Source

𝐹𝑞 = ℎ𝑔

𝑭 =

2.55 mm 0.6 mm Modify

Bandpass filter

To maintain the high light intensity

𝑰

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Detecting pressure

ROI detection and create the PPG signals PPG Identify the peaks and troughs Calculate peak-to- peak ratio 95 %

Collecting raw data

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Algorithms

PhO2

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App overview

PPG display Image frame

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SLIDE 23

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SLIDE 24

In-lab experiments

3 males, 3 females
5 times performs the hyperventilation (a breath

holding technique to reduce oxygen).

Totally 560 samples.

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SLIDE 25

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PhO2 vs. Existing apps

SpO2 (%) Measurement Indices DigiDoc SpO2 (%) Measurement Indices iHealthCare SpO2 (%) PhO2 Time (s)

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Experimental results

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3.5%

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In clinic experiment

In hospital experiment with patient.

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SLIDE 28

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Fine-grained evaluation of the patient

Low Oxygen Level Coughing

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Heat Reduction Evaluation

Hand multimeter Thermalcouple Probe

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Output temperature of different add-on designs

10 20 30 40 50 60 Without Banpass Filter With Bandpass Filter 58.9 45 38.5 36.8 40.3 37.6 Temperature (Celsius) Large Tunnel Small Tunnel Multiple Small Tunnels

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Conclusion ❑Accurately measuring oxygen level using low-cost optical film filters. ❑Detect the appropriate contact pressure between finger and phone’ camera. ❑3D-printed add-on to handle the problem of light scattering and finger movement.

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SLIDE 32

Application for optical light based sensing

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Cholest- erol

Optical light based sensing

Urea Lactate Water Alcohol Glucose

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Smartphone based Blood Oxygen Level Measurement using Near-IR and RED Wave-guided Light

Nam Bui, Anh Nguyen, Phuc Nguyen, Hoang Truong, Ashwin Ashok, Thang Dinh, Robin Deterding, Tam Vu

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