Transcript Document 7298632

Anup Pillai
Dhanya Premkumar Nair
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Current blood pressure sensors in use
Background
Long-Term Implantable Blood Pressure
Monitoring System and Advantages
Wireless Battery less In VIVO Blood Pressure
Sensing Micro system and Advantages
System Architecture
Our Objectives
Timeline and Division of work
Conclusions
To diagnose critical medical conditions like
hypertension
-causes strokes, heart attacks, heart failures
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Low blood pressure causes hypotension,
which results in dizziness, fainting or shock
Auscultatory method
Mercury Manometer
With the new sensor, no cuff is
required
Device takes advantage of the
method called pulse wave
velocity which allows blood
pressure to be calculated by
measuring the pulse at 2 points
along an artery
This was developed at MIT's
d'Arbeloff Laboratory for
Information Systems and
Technology
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Current blood pressure sensors in use
Background
Long-Term Implantable Blood Pressure
Monitoring System and Advantages
Wireless Battery less In VIVO Blood Pressure
Sensing Micro system and Advantages
System Architecture
Our Objectives
Timeline and Division of work
Conclusions
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In vivo-Latin for “within the living”
Experimentations are done using a whole,
living organism
In vivo monitoring is critical for developing
effective treatments
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Long-Term Implantable Blood Pressure
Monitoring System
Wireless Battery less In VIVO Blood Pressure
Sensing Micro system
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Current blood pressure sensors in use
Background
Long-Term Implantable Blood Pressure
Monitoring System and Advantages
Wireless Battery less In VIVO Blood Pressure
Sensing Micro system and Advantages
System Architecture
Our Objectives
Timeline and Division of work
Conclusions
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The system employs an instrumented elastic cuff,
wound around a blood vessel
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Operates in a linear “diameter v.s. pressure” region of
the vessel for real time blood pressure monitoring
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The elastic cuff is made of soft bio-compatible
rubber, filled with bio-compatible insulating fluid
with an immersed MEMS pressure sensor
The MEMS sensor detects the vessel blood pressure
wave form with a constant scaling factor,
independent of the cuff bias pressure exerting on the
vessel.
MEMS
sensor
Insulating
Liquid
Vein
Cuff
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This technique avoids vessel insertion
Also substantially minimizes vessel
movement restriction due to the soft cuff
elasticity
Attractive for minimizing long-term
adverse biological effects
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Current blood pressure sensors in use
Background
Long-Term Implantable Blood Pressure
Monitoring System and Advantages
Wireless Battery less In VIVO Blood Pressure
Sensing Micro system and Advantages
System Architecture
Our Objectives
Timeline and Division of work
Conclusions
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Wireless powering and data telemetry are also
incorporated in the micro system
This eliminates the need of external wire
connections and any bulky battery
The micro system can be used to obtain
reliable measurements without suffering from
stress induced distortion
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Current blood pressure sensors in use
Background
Long-Term Implantable Blood Pressure
Monitoring System and Advantages
Wireless Battery less In VIVO Blood Pressure
Sensing Micro system and Advantages
System Architecture
Our Objectives
Timeline and Division of work
Conclusions
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Current blood pressure sensors in use
Background
Long-Term Implantable Blood Pressure
Monitoring System and Advantages
Wireless Battery less In VIVO Blood Pressure
Sensing Micro system and Advantages
System Architecture
Our Objectives
Timeline and Division of work
Conclusions
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The sensor specified in the background exhibits
increased noise levels
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The transmitter of the same dissipated a 80% of
the system power
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Our objectives are:
a) To design a similar sensor which exhibits less
noise levels
b) To design a better and more power efficient
transmitter for the sensor
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To find a solution which exhibits less noise
levels
We began by investigating the reason for
the high noise levels in the current design
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Animal body vapor penetration into the
device
Affect the functioning of the electrical
connections within the sensor.
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The high impedance node can be highly
sensitive to vapor penetration
Electrical connections between the sensor
diaphragm and IC chip
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Protection for moisture penetration is
required for the sensor diaphragm as well as
the electrical connections between the sensor
diaphragm and IC chip.
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A passivation layer, such as silicon dioxide
(SiO2) and silicon nitride (Si3N4), can be
deposited on the top of diaphragm.
An encapsulant material with strong
moisture resistance can be used to protect
the bond wires between the sensor and IC
before applying silicone passivation layer.
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To design a better and more power efficient
transmitter for the sensor
In the microsystem, an oscillator based FSK
transmitter was employed for data telemetry
This transmitter was on throughout and
hence resulted in 80% power dissipation
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To use a transmitter operating with a low
duty cycle
One can also use a transmitter with an
increased bandwidth
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If the sampling frequency is 2 kHz, with data
rate of 48 kbps, corresponding bit rate is 24
per 0.5 ms
This is the current specification for the
system
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Instead if we the transmitter is designed to be
on for 0.05 ms and off for the remaining 0.45
ms
This results in one order magnitude power
reduction at increased data rate of 480 kbps
This corresponds to 72% overall system
power reduction
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Current blood pressure sensors in use
Background
Long-Term Implantable Blood Pressure
Monitoring System and Advantages
Wireless Battery less In VIVO Blood Pressure
Sensing Micro system and Advantages
System Architecture
Our Objectives
Timeline and Division of work
Conclusions
February
Research
project
topic and
preparatio
n for
report 1
Report 1
Objective 1
Presentatio
n2
Objective 2
Final
Report
March
April
May
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First Objective:
To design a similar sensor which exhibits less
noise levels-A. Pillai
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Second Objective:
To design a better and more power efficient
transmitter for the sensor-D. Nair
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A review of current in-vivo blood pressure
sensors was presented in this review study
We identified the potential problems with
existing solutions
We have proposed two solutions that will
enhance the performance of the current
design
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