External Use

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Xtrinsic Pressure Sensors in the

Medical Market

FTF-HCR-F0174

A P R . 2 0 1 4

Miguel Salhuana | Systems Engineering

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External Use 1

Quick Introduction

• Employed at Motorola / Freescale Semiconductor from February 1995 to

the present, where I’ve had multiple careers. Most recently:

− SoC Integration, Synthesis, Timing Closure and Verification

− Sensor Applications / Product Definition / System Architecture

− basically, solving applications, systems and implementation problems

• Miguel.Salhuana@freescale.com

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Agenda

• How a Pressure Sensor Works

• Pressure Sensor Selection

• Medical Applications

• Development Tools

• Q&A

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Pressure Sensor Basics

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Sensor Basics

• A sensor is a device that detects either an absolute value or a change in a physical or electrical quantity, and converts that change into a useful input signal for a decision making center.

• Pressure (p) is the force (F) applied to a unit area of surface (A) in a gas, liquid or solid. P = F/A

• Atmospheric (Barometric) pressure is due to the weight of the atmosphere (air and water vapor) on the earth’s surface.

Data Processing,

Control, and Connectivity Sensor Input

Output

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Sensor Basics – How Does It Work?

PRT – Piezo Resistive Transducer

Well-established process

temperature variations

A

B

C

D

VIN

Output mV

VOUT

R1

R3 R2

Rg

VOUT = VIN [ R3

R3 + Rg

R2

R1 + R2 ]

Apply Kirchhoff voltage and current laws:

C to V

Converter

P-CELL

PREF

Capacitive Pressure

Transducer Low power consumption

Small Size PCELL

Px

Uncompensated

Compensated

Integrated

TPMS

Satellite Airbag

Timing

Associated System

Change in Resistive Diaphragm

leads to Voltage Shift.

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Sensor Basics – How does it Work?

Pressure Sensor Cross Section

Gauge or Differential Die in the Basic Chip Carrier Package

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Sensor Basics – How Does It Work?

How the Diaphragm Moves • The difference in positive pressure

between the sealed cavity & the

outside pressure, causes the

diaphragm to deflect inward.

• The piezo resistive strain gauge

resistors, located in the diaphragm

itself, detects the deflection of the

diaphragm as a mechanical stress,

resulting in a voltage difference.

• This voltage difference is processed

and amplified to provide the proper

output.

• Sensitivity is primarily a function of

the dimensional characteristics of the

diaphragm itself, especially its

thickness.

No pressure difference

Positive pressure applied

P1

P2

P2

P1

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Sensor Basics – Measurements

Differential P1

P2

Gauge

Absolute

Vacuum

P1

P1

P2 = ATM

Constraint Wafer

For All: P1>P2 for positive voltage output

• The difference in pressure between two points is measured where pressure is applied to both sides of sensor.

• P2 is exposed to the atmosphere and P1 is where pressure is applied.

• Pressure is applied to the top of the die while the bottom of the die is a vacuum sealed reference.

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Sensor Basics – Units

• Pressure (p) is the force (F) applied to a unit area of surface (A) in a gas, liquid or solid

p = F/A

• Atmospheric (Barometric) pressure is due to the weight of the atmosphere (air and water vapor) on the earth’s surface

• The conversions for the most commonly used units are:

1 atm = 101.325 kPa = 760 mmHg = 14.6960 psi

1 psi ~ 28” H2O ~ 70cm H2O ~ 7kPa

bar psi cm water inch of

water

foot of

water

kilopascal

(kPa)

bar 1 14.504 1019.74 401.474 33.456 100.0

psi 0.069 1 70.309 27.680 2.307 6.895

cm of water 0.000 980 0.014 1 0.394 0.033 0.098

inch of water 0.002 491 0.036 2.54 1 0.083 0.249

foot of water 0.029 890 0.434 30.48 12.021 1 2.989

kilopascal

(kPa) 0.01 0.145 10.197 4.015 0.335 1

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Sensor Basics – Question

Who arrived here on a flight?

Phoenix

Drink a bottle of

water, squeeze and

tighten the cap.

Plane

What happens

to the bottle on

the flight?

Dallas

You have arrived,

what does the bottle

look like now?

? ?

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Sensor Basics – Question

Who arrived here on a flight?

Phoenix

Hint:

Phoenix is typically

at 97kPa

Plane

Hint:

Flight Cabin is

typically set to

77kPa

Dallas

Hint:

Dallas is typically

at 102kPa

? ?

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Sensor Basics – Question

Who arrived here on a flight?

Phoenix

Hint:

Phoenix is typically

at 97kPa

Plane

Hint:

Flight Cabin is

typically set to

77kPa

Dallas

Hint:

Dallas is typically

at 102kPa

? ?

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Pressure Sensor Selection

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Sensor Selection – Our Current Products

Uncompensated

Integrated

Design Advantages Design Considerations

• High sensitivity

• Lowest device cost

• Low-level output allows flexibility

of signal conditioning

• Device to device variation in offset

and span

• Temp-compensation circuitry required

• Signal conditioning / amplification

of signal needed

• Reduced device to device

variations in offset & span

• Reduced temperature drift in offset

and span

• Low-level output allows flexibility

of signal conditioning

• No amplification needed,

direct interface with MCU

• Signal conditioning, calibration of

span & offset, temperature

compensation included on-chip

• Lower sensitivity due to span

compensation (compared to uncomp)

• Priced higher than uncomp

• Required signal conditioning /

amplification of output signal

• Priced higher than

uncompensated and

compensated devices

• Lower piece part count on system

PCB

Compensated

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Sensor Selection – Package Options

MPAK

MPAK Axial Port

Super

Small

Outline

Package

(SSOP) Dual

Port

Case

423A

Case

482 Vacuum

Port

Small

Outline

Package

(SOP) Side

Port

Dual

Port

Through

Hole

Axial Port

Case

1317

QFN

Tire

Pressure

Monitor

Axial

Port

Through

Hole 482B Axial

Port

Unibody Medical

Chip Pak

Through

Hole

Axial Port

Through

Hole

Axial Port

LGA

MPL3115A2

5x3x1.2mm

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Sensor Selection – Selecting the Best Pressure Sensor

Step 1: Use Case

• Measurement type: Absolute, Gauge or Differential?

• Pressure range required?

• Sensitivity / Accuracy required?

• Integrated, Compensated, Uncompensated?

Step 2: Environment

• When does the system take a measurement?

• Does the temperature change drastically?

• Is the sensor exposed to chemicals?

Step 3: Implementation Details

• Autozero the pressure sensor (AN1636)

• Media compatibility with the sensor (AN3728)

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Medical Applications

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Blood Pressure Package

Key Features

• Low Cost

• Integrated temperature

compensation and calibration

• Ratiometric to supply voltage

• Polysulfone case material

(Medical, Class V Approved)

• Provided in easy-to-use

tape and reel

Disposable Pressure

Sensors MPX2300DT

A standard invasive blood pressure

monitoring kit - sterile, single-use kits

that relay blood pressure information from

a pressure monitoring catheter to a patient

monitoring system.

Freescale’s MPX2300DT is a low cost, high

volume, miniature pressure sensor package

for the application.

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Blood Pressure Monitors

Position cuff on left

wrist with left thumb

facing upward

Press start button.

Position sensor

detects correct

placement of arm in

relation to the heart.

Once wrist is in the

correct position the

cuff will inflate and take

the measurements.

Reading is displayed

on the LCD screen

Bleed Valve Valve

Control

Motor

Display

Pressure

Sensor

Keypad

Tilt Sensor (Accelerometer)

Voltage

Regulation

Power

Source

MCU

Motor

Control

Bluetooth

Radio

Pressure Monitoring MPXV5050GP

MPXM2053GS

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Negative Pressure Wound Management

Negative Pressure Wound

Management or Closed Wound

Suction (CWS) is a non-invasive

treatment by which controlled

localized negative pressure

(suction) is delivered to a wide

variety of acute, sub-acute, and

chronic wounds.

Negative

Pressure

Wound

Therapy

(N.P.W.T.)

Unit

Air Pressure Management System MPL3115A2

MPXM2053GS

MPXV5100GC6U

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MPL3115A2 in Wound Management

The MPL3115A2 digital pressure sensor essentially can act as a vacuum sensor at altitudes below 10,000 Feet. Broader pressure range is achieved closer to sea level.

MPL3115A2 as

vacuum sensor

MPL3115A2 as

barometric sensor

PUMP

Suction Pressure

about 40 kPa below

Po at 61 kPa

Atmospheric

Pressure, Po at

about 101 kPa

PCB

Wound

BANDAGE

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Patient Monitoring

MPXM2051 Key Features

• Pressure range 0~50kPa gauge

• Temperature compensated

over 0°C to +85°C

• Linearity: +/- 0.3%

• Full scale span: 40 +/- 1.5mV

• Offset: +/- 1.0mV

• Available in easy-to-use tape

and reel

• Ratiometric to supply voltage

• Gauge ported

Blood Pressure Monitor Module MPXM2051 (Measurement)+MPXM2053

(Protection) MPXV5050

CO2 Module MPXV2010 (Flow measurement)

MPL3115A2 (Digital Barometer)

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Respirator Machine

Freescale IPS for

Respiratory Device:

• Wide pressure range

product portfolio from negative

to positive pressure.

• Low pressure range family

(+/-2kPa, 4kPa, 6kPa, 10kPa)

offer design flexibility.

• Ideally suited for microprocessor

or microcontroller-based

systems

• Easy to implement

(no amplifier needed)

• Digital barometer MPL3115A2

offer <1.0kPa accuracy

Air Flow Measurement MPX2010

MPXV7002DP

MPXV5004DP

Barometric Measurement MPXH6115A

MPL3115A2

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Medical Bed/Air Mattress

Prevents • necrosis of the muscle

• pressure sores or

• ulceration

Pressure Monitoring MPX5010DP

MPXM2010GS

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Blood Circulation Therapy

The system provides the optimal

hemo-dynamic profile by applying

intermittent, sequential pressure

to the patient’s leg in a systematic

pattern, increasing the peak venous

velocity (PVV) of venous blood flow

and reducing the risk of clot formation.

Continuous

Enhanced

Circulation

Therapy

(C.E.C.T.)

System

Air Pressure

Management System MPX2010

MP3V5010G

MP3V5050G

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Sleep Apnea

• Positive airway pressure

(PAP) is a method of

respiratory ventilation

used primarily in the

treatment of sleep apnea.

• Barometric measurement

is also critical in some

applications to avoid

altitude deviation.

Continuous

Positive

Airway

Pressure

(C.P.A.P.)

Air Pressure Management System MPXV5004GC6T1

MPXV7002DP

Barometric Measurement MPL3115A2 (Digital barometer)

Cycle of Obstructive Sleep Apnea

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Development Tools

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Medical AFE Demo/Development Kit

Freescale Medical Suitcase • complete development platform

• Tower System eases development of medical applications

• fully integrated solutions set

Has 6 different Analog Front Ends • each focused on a specific medical application

• allows code and hardware reuse

• significantly reduces time to market

Applications Include • 1-Lead ECG

• pulse oximeter

• blood pressure monitor

• glucometer

• spirometer

• ultrasound digital stethoscope

Just plug and play –

ask a sales manager

for a demo today!

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MED-BPM

Complete solution for

design of blood pressure

monitor applications

Features

• Includes isolation circuitry for air

pump and escape valve

• Designed for operation at 3V – 3.3V

• Integrated Freescale

MPXV5050GP pressure sensor

• Schematics, gerber files,

and BOM available

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MED-SPI

• Demonstrates basic

implementation of spirometer

solution

• Includes MPXV7025DP

differential pressure sensor

facilitating air flow measurement

calculation lung capacity

Features

• Minimal components

• Easy to implement

• Schematics, gerber files,

and BOM available

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Xtrinsic Sensor Expansion Boards

Differentiators • First 12-axis Freedom Platform

• First with Sensor Fusion Toolbox Android app

• Scalable toolset with 3 options shown (see next slide)

• Plugs into Freedom Development Tools

FRDM-FXS-MULTI Xtrinsic Shield board • MPL3115A2 – Altimeter/pressure sensors

• MMA8652 – 3-Axis Accelerometer 2x2mm

• FXAS21000 – 3-Axis Gyroscope

• FXOS8700 – 6-axis Ecompass Sensor (accelerometer +magnetometer)

• FXLS8471 – 3-Axis Accelerometer 3x3mm with SPI

• MMA955x – Intelligent Sensor with 3-Axis accelerometer and 16Kb flash (ADD 32 bit micro)

• MAG3110 – 3-Axis Magnetometer 2x2mm

Relevant Documentation • Quick Start Guide and installations instructions provided

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Xtrinsic Sensor Expansion Boards

Part Number Description Pricing

FRDM-FXS-MULTI-B* Xtrinsic Sensor Expansion board w/ Bluetooth and Battery, MPL3115A2 MMA8652 FXAS21000 FXOS8700 FXLS8471 MMA955x MAG3110

$125

FRDM-FXS-MULTI* Xtrinsic Sensor Expansion board MPL3115A2 MMA8652 FXAS21000 FXOS8700 FXLS8471 MMA955x MAG3110

$50

FRDM-FXS-9AXIS* Xtrinsic Sensor Expansion board with only 2 sensors : FXAS21000 FXOS8700

$30

Kinetis KL25z compatible Xtrinsic Sensor Expansion Boards

KL25z

*Boards are compatible with the KL25z, KL26z and the K20D50M Freedom Boards.

FRDM-FXS-

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Differentiators

• Proven technology and reliability

• Unique technical capabilities

− Broad technical portfolio for sensing ranges

− Packaging capabilities and varieties

− 30+ years of sensor design experience

• Development tool chest for fast prototyping and development

• MCU partnership to deliver complete embedded system solutions

• Complete system solution with MCU, Sensors, Analog, Networking

and RF communication.

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© 2014 Freescale Semiconductor, Inc. | External Use

www.Freescale.com

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© 2014 Freescale Semiconductor, Inc. | External Use

www.Freescale.com

Backup Slides

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Sensor Integration + Intelligence =

Xtrinsic Sensing Solutions

• Increasing levels of integration

− Sensor signal processing

− Nonvolatile storage

− I/O interfaces

• Intelligent Software Framework

− Data acquisition

− Power management

− Connectivity

• Increasing levels of intelligence

− Programmability

− Auto-calibration

− Sensor fusion

− Third-party software ecosystem

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Sensor Basics – Ranges

Water level sensing in Washing Machines 40cm of H20 4

Engine Map Sensor 3 to 48psi 20 to 304

Medical Respiratory 0.5 to1.45psi 4 to 10

Altimeter/Barometer 2.9 to18.8psi 20 to 130

Tire Pressure Monitoring 14.5 to 120psi 100 to 800

Sea Level 1atm=14.9psi 101.3

Dead Sea-Lowest point on earth -1300ft 15.4psi 106

Everest-Highest point on earth +30,000ft 4.8psi 33

Space-Low density Extremely low close to Vacuum 0psi ~0

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Sensor Basics – How Does It Work?

Diaphragm

Ion-implanted

Strain

Gauge

Single Chip Integrated Silicon Pressure Sensor

Signal

Conditioning

Circuit

Our IPS Technology

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Sensor Basics – Absolute Sensors

Dead sea – Lowest point

on earth -1,300ft, 106kPa

Everest - Highest point

on earth +30,000ft, 33kPa

Barometer

Altimeter

Tire Pressure

Engine Control

• Each needs a pressure measurement that

is compared to a fixed reference (vacuum)

• Sensor is in an enclosed environment with a

pressure medium

Point B

Point A

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Sensor Basics – Gauge Sensor

• Each needs a measurement that compares the

barometric pressure in its surroundings to the

measurement pressure

• In general, anything below 10 psi (70 kPa)

Blood Pressure

Water Level

Leak Detection

Test Equipment

Atmospheric pressure

Sealed tube of air/water column

Pressure Sensor measuring with reference to atmospheric pressure.

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Sensor Basics – Differential Sensor

• Each requires a comparison of the

pressure between two ports of the sensor

• Flow measurement

HVAC Applications

Air Flow

Filter Pressure

Pressure Drop

DP= f(V)

Pressure Sensor measuring with a difference in pressure

between two pressure points

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Sensor Selection – Our Current Products

MPX5010DP

COMPENSATED + CALIBRATED + AMPLIFIED = INTEGRATED

MPX2010DP

COMPENSATED

& CALIBRATED

Temperature

compensation Amplification

Amplification

MCU

MCU

MCU

Output

Output

Output

MPX10DP

BASIC ELEMENT

Altitude: MPXM2102A

Altitude: MPXA6115A

MPX5100A

MPX4115A

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Sensor Selection – Our Current Products

M PX V 5 010 G C 6 U DEVICE CATEGORY M Qualified standard S Custom device P,X Prototype device

FAMILY - Uncompensated 2 Temp Comp & Calibrated 4 - 6 Amplified

Maximum Rated Pressure (kPa) except MPX2300 expressed in mmHg.

MEASUREMENT TYPE A Absolute D Differential G Gauge V Vacuum

SHIPPING METHOD

- Trays

T1 Tape & Reel

U Tube

PORTING OPTION

P Side Port Porting

DP Differential Porting

VP Vacuum side Porting

C,S Axial port

SOP LEAD BENDING

6 Gull wing leads

7 Leads 84° bent towards

the bottom

PRESSURE SENSORS

PACKAGE SELECTION - Unibody A Absolute Small Outline Package (SOP) C Chip Pak H Super Small Outline Package (SSOP) L LGA M MPAK V Vented Small Outline Package Y CMOS Z Media Resistant Gel

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TWR-

K53N512

TWR-SER

TWR-LCD

Tower

System

EBI

USB

Includes Freescale Technology

Medical

Connector

MED-SPO2

MED-EKG

MED-SPI

MED-BPM

MED-GLU

MED-

STETH

Medical Suitcase Block Diagram

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High-End Blood Pressure Monitor (BPM) + spirometer (highlight freescale parts) add pressure sensor

Kinetis K50

VREF PDB

2 x ADC ACMP

TRIAMPS

OPAMPS

SPI

TSI

LCD

CNTRL

Segment

Display

External

Bus

Touch

Pad

DC

Brush

Motor

CNTRL

Graphic

Display

NVM

Pump

motor

Bleed

valve

ARM

Cortex

M4™ CPU

SW

Filter

Pressure

Sensor

MPXV5050GP

USB Ethernet

Analog Sensors Peripherals

Optional Internal Modules

Pressure

Sensor

MPXV7025DP

500 Hz

Low

Pass

Filter

Add a spirometer

with the 2nd ADC

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Blood Pressure Monitor

• A blood pressure monitor uses

techniques such as oscillometric

methods and Korotkoff’s

measurements to measure

blood pressure

• The oscillometric method consists

of measuring the oscillations in

pressure inside a cuff that the

patient wears. The Korotkoff

method is based on listening to

sounds when taking blood pressure

• Automatic blood pressure

monitoring conducted at home is

increasingly used in the diagnosis

and management of hypertension

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Design Challenges – Blood Pressure Monitor

Problem Solution

Measurement accuracy Increase the ADC resolution

Battery oriented Extreme low power consumption specially

Appropriate display Segment or graphic LCD display capability

Pressure Sensor Medical-grade pressure sensors, signal conditioning inside

the MCU

Connectivity Wires and/or wireless communication capability

Low cost BOM reduction, hardware design optimization

Algorithm complexity Cost-effective CPU performance

Added value & differentiators Internal sensing, touch sensing

Motor Control External controller via SPI, or with the internal TPM module

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MED-BPM State Measuring Flow Diagram

MAP (Mean Arterial Pressure)

Maximum Amplitude of all Pulses

Max pressure not reached

Find higher

point in pulse

Ignore first

samples

Find lower

point in pulse

Store pulse

amplitude and

cuff pressure

value

Calculate

arterial

pressure

values

Show Results

Stop inflating

cuff and open

escape valve

70% of MAP. Pressure in cuff

Above MAP

50% of MAP. Pressure in cuff

Below MAP

• MED-BPM demo uses Ramp-Up method (variation of oscillometric).

• Air pump starts to inflate the cuff.

• While inflating, for each oscillation the main cuff pressure is taken and the oscillation amplitude is saved.

• When the pressure has reached a maximum value, motor stops inflating and valve opens in order to deflate the cuff.

• While cuff is deflating, calculations are performed.

• All the pulses are checked in order to find the one with the biggest amplitude.

• Pulse with the biggest amplitude represents the MAP (Mean Arterial Pressure), and the main cuff pressure recorded during this pulse is registered as the MAP.

• Systolic and Diastolic arterial pressures are calculated.

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Demo: MED-BPM

Air

Pump

Arm Cuff

Air

Valve

Pressure

Sensor

MP3V5050

GPIO

GPIO Op

toco

uple

r

Low

Pass Buffer with

internal

OpAmp

AD

C

Signal

Amplifier

with

internal

OpAmp

High

Pass

ADC

Low

Pass

Freescale Part

MM/K5X Internal

Non electrical connection

Measure pressure from cuff

Amplify pulses to detect

maximum peaks

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MED-BPM

MED-BPM Running

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MED-EKG

• Auxiliary board for development of electrocardiography and heart rate monitoring

• Speeds up development time, scalable and adjustable to final product needs

Features

− Tower System compatible

− Integrates all required components for electrocardiograph development

− Four finger electrodes

− External electrode capable for increased accuracy

− MC56F8006 DSC included on board

www.freescale.com/MED-ECG

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MED-SPO2

• Pulse oximetry

development ideal for

SpO2 measurement or

beats per minute (bpm)

determination using non

invasive procedures

Features

− Tower System compatible

− Full integration

− Size optimized

www.freescale.com/MED-SPO2

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MED-GLU

− Single-board glucometer solution

− Eases design

Features

− Size optimized

− Tower System compatible,

opening complete suite of

solutions including

serial communications

LCD displays

wireless connectivity

− Schematics, gerber files,

and BOM available

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MED-STETH

• Complete digital stethoscope solution using ultrasonic waves

• Complimentary to design of fetal heart rate monitors

Features

− Tower System compatible

− Application software available

− Designed for use with TWR-LCD,

a 16-bit color TFT-LCD display

for vivid graphics

− Schematics, gerber files,

and BOM available

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External Use 55

Nonin Pulse Ox

MC9S08GP32

The Home Health Hub Platform

868MHz RF

Thermometer

HHH Panic Alarm

MC12311

Wired connection

Wireless connection

Medical monitoring

WWW connection

TELE-HEALTH

Weight Scale Blood Glucose

Meter

Bluetooth

Low Energy Bluetooth

SPP

Bluetooth

HDP

HHH Ref Platform

Gateway

i.MX28

i.MX53 Tablet

With Medical User

Interface

Physician

Social Networking

Monitoring Center

Loved Ones

Social Network

Home Health Hub Ref Platform Expansion Capabilities Smart Plugs

Smart Appliances

Safety/Security

Lighting Control

Local Display

HOME AUTOMATION

Ethernet

Blood Pressure

Monitors

USB

PHDC

HealthCare

TM

© 2014 Freescale Semiconductor, Inc. | External Use

www.Freescale.com