MetaHealth
Biometric Monitor Datasheet
Version 2.0
MetaHealth Biometric Monitor
Reflective photoplethysmography (PPG) and Galvanic skin response (GSR) Module
for Wrist, Arm and Ankle Devices
Applications
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Features
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Wearable Devices
Mobile devices
Smart Watches
Lifestyle/Activity Bands and trackers
Wrist, Forearm and Upper Arm Bands for
Sports
Research
Health, fitness, and medical applications
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Optical heart rate (HR)
Galvanic skin response (GSR)
Small dev board size (24.0 mm^2 x 3.0 mm)
Small system size (10.0 x 5.0 x 1.0 mm)
Fast read cycles and setup time
< 2.5mA sensor current consumption during
HR reads
< 5uA in sleep mode
MetaHealth is a new generation of biometric
monitoring technology developed by MbientLab,
Inc.
The GSR and HR sensor can be used for any science
experiment, product development, or activity which
utilizes the natural galvanic skin response (skin
conductance) and heart rate in the fields of
medicine, fitness, health, biology, physiology,
psychology, etc.
Galvanic skin response (GSR), or skin conductance, is a measure of the changes in the skin’s conductivity due to
a stimulus, whether it is a picture, smell, sound, touch, etc. Sweat glands are controlled by the sympathetic
nervous system which release small amounts of sweat when a stimulus is sensed. This is how the GSR sensor can
relate psycho-activity to sweat gland activity.
Reflective photoplethysmography (PPG) is a measure of your heart rate and can be translated to BPM (beats per
minute) and HRV (heart rate variability). The PPG sensor is a fully integrated optoelectronic sensor, specially
designed and optimized for heart rate and pulse sensing. It features three LEDs – green (535 nm) - and a large
area photodiode (PD) to maximize signal level. The device design includes a light barrier to minimize internal
crosstalk thus enhancing the signal-to-noise ratio.
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MetaHealth
Biometric Monitor Datasheet
Version 2.0
The module design brings together the best available sensors and parts of a successful biometric sensor system:
emitter/detector sensor electronics, conductive lead electronics, advanced algorithms to remove noise during
heavy activity, and low-power optimal design for wrist based sensing.
MetaHeath allows you to easily integrate highly intelligent biometric sensors into your wearable products for
accurate and meaningful fitness and lifestyle user experiences for your customers or your research.
The sensor comes pre-calibrated so you can start experimentation right out of the box.
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MetaHealth
Biometric Monitor Datasheet
Version 2.0
PPG - Heart Rate Sensor
PPG Construction
PPG Block Diagram
The PPG sensor is designed to operate close to human skin, any additional air-gap between human skin and the
sensors surface can reduce the signal strength. Operating the PPG sensor with a cover glass might cause optical
crosstalk. Crosstalk needs to be reduced or avoided as it reduces the signal-to-noise ratio. For larger air-gaps a
proper optical aperture design or light baffles between the LEDs and the sensor might be required.
The PPG sensor is completely safe for humans as well as pets. The radiated light doesn’t present any harm to the
human skin / body (no ultraviolet light content) and the radiation is well below any critical level concerning eye
safety regulations (at typical pulse currents below 1A).
PPG Block Diagram
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Biometric Monitor Datasheet
Maximum Ratings (TA = 25 °C)
Parameter
Symbol
Values
Unit
Operating temperature range
Top
-40 … 85
°C
Storage temperature range
Tstg
-40 … 85
°C
SED withstand voltage
VESD
2
kV
VR
5
V
Forward current (single emitter operation)
IF (DC)
25
mA
Forward current (all emitters active)
IF (DC)
15
mA
Surge current (tp = 100 μs, D = 0)
IFSM
300
mA
VR
16
V
General
Green Emitters
Reverse voltage
Detector
Reverse voltage (IR = 100 μA, Ee = 0 mW/cm2)
The emitter is comprised of 3 green LEDs but only one is needed to effectively measure heart rate and conserve
battery. All LEDs inside the PPG sensor have very tight wavelengths specifications and feature low temperature
dependent drift (0.13 nm/K) as well as narrow spectral bandwidth.
Characteristics (TA = 25 °C)
Parameter
Symbol
Value
Unit
Green Emitter (single emitter)
Wavelength of peak emission (IF = 20 mA)
(typ.)
ʎpeak
530
nm
Centroid Wavelength (IF = 20 mA)
(typ.
(max.))
ʎcentroid
535 (±10)
nm
Spectral bandwidth at 50% of Imax (IF = 20 mA)
(typ.)
Δʎ
34
nm
Half angle
(typ.)
ϕ
± 60
°
Rise and fall time of Ie (10% and 90% of Ie max) (IF = 100 mA, tp = 16
μs, RL = 50)
(typ.
(max.))
t r, t f
32
ns
Forward voltage (IF = 20 mA)
(typ.)
VF
3.2 (≤ 3.7)
V
Reverse current (VR = 5 V)
(typ.)
IR
N/A
μA
Radiant intensity (IF = 20 mA, tp = 20 ms)
(typ.)
Ie
1.4
mW / sr
Total radiant flux (IF = 20 mA, tp = 20 ms)
(typ.)
φe
3.4
mW
Temperature coefficient of ʎcentroids (IF = 20 mA, -10°C ≤ T ≤ 100°C)
(typ.)
TCʎcentroid
0.02
nm / K
Temperature coefficient of VF (IF = 20 mA, -10°C ≤ T ≤ 100°C)
(typ.)
TCV
-4.0
mV / K
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Biometric Monitor Datasheet
The detector photodiode features a low dark current, suitable for low noise applications. The photodiode
current is amplified and converted into a voltage with an external trans-impedance amplifier. The low
capacitance and the fast response of the photodiode make it suitable for short pulse operation to minimize
power consumption.
Characteristics (TA = 25 °C)
Parameter
Symbol
Value
Unit
Detector
Photocurrent (Ee = 0.1 mW/cm2, ʎ = 535 nm, VR = 5 V)
(typ.)
IP,535
0.42
μA
Wavelength of max. sensitivity
(typ.)
S max
920
nm
Spectral range of sensitivity
(typ.)
10%
400 … 1100
nm
Radiation sensitive area
(typ.)
A
1.7
mm2
Dimensions of radiant sensitive area
(typ.)
LxW
1.3 x 1.3
mm x mm
(typ. (max.))
IR
1 (≤ 5)
nA
Dark current (VR = 5 V, Ee = 0 mW/cm2)
Spectral sensitivity of the chip (ʎ = 535nm)
(typ.)
S
0.27
A/W
Open-circuit voltage (Ee = 0.1 mW/cm2, ʎ = 535 nm)
(typ.)
VO,535
240
mV
Short-circuit current (Ee = 0.1 mW/cm2, ʎ = 535 nm)
(typ.)
ISC,535
0.40
μA
Rise and fall time (VR = 3.3 V, RL = 50 ῼ, ʎ = 535nm)
(typ.)
t r, t f
42
ns
Forward voltage (IF = 10 mA, E = 0 mW/cm2)
(typ.)
VF
0.9
V
Capacitance (VR = 5 V, f = 1 MHz, E = 0 mW/cm2)
(typ.)
C0
5
pF
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Biometric Monitor Datasheet
GSR – Conductance based Skin Response Sensor
GSR Pads Construction
GSR Usage Diagram
The GSR sensor is designed to operate close to human skin; measuring the electrical conductance of the skin.
The user must put his skin (preferably fingers) on the leads (exposed and electrically conductive pads on the
board) or use preferred electrodes. Conductance is measured from the finger, to the pads, to the ADC.
The skin response time from the sudden effect is between 0.1 to 0.5 seconds.
The level of response changes dramatically from one person to another. The user must be still while the sensor
is in use.
GSR Block Diagram
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Biometric Monitor Datasheet
Maximum Ratings (TA = 25 °C)
Parameter
uS
General
Range and operation modes
0 to 10
ADC Resolution
16 bit
Resolution
10 nS
Max sample rate (S/sec)
100
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Biometric Monitor Datasheet
For additional information please contact:
hello@mbientlab.com
www.mbientlab.com
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MbientLab, Inc. reserves the right to make technical changes to its products or example designs as part of its
development program.
While every effort has been taken to ensure the accuracy of the contents of this document, MbientLab cannot
accept responsibilities for any errors.
MbientLab technology is not designed or authorized for use in life support, medical, or safety critical
applications. MbientLab makes no warranty, representation, or guarantee regarding the suitability of its
products for any particular purpose. MbientLab assumes no liability arising out of the application or use of
any product or circuit, and specifically disclaims any and all liability, including without limitation
consequential or incidental damages.
The publication or transfer of this information does not imply that any license is granted under any patent or
other rights owned by MbientLab, Inc. This document should be held in confidence per NDA and/or all other
relevant agreements.
Products, services and names used in this document may have been trademarked by their respective owners.
MetaWear, and MetaHealth are registered trademarks of MbientLab, Inc. and may not be used for any purpose
without the express prior written consent of MbientLab, Inc.
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