NASA Portable Wireless ECG MonitorNASA Portable Wireless ECG MonitorBME 460: Senior DesignBME 460: Senior Design

Department of BiomedicalDepartment of Biomedical EngineeringEngineeringThe City College of the City University of New YorkThe City College of the City University of New York

140140thth Street and Convent Ave., Street and Convent Ave., New York, NY 10031New York, NY 10031

Concept Selection and Project Updates Thursday February 14th, 2008

Wireless Electrocardiogram Wireless Electrocardiogram ProjectProject

OverviewOverview

•• IntroductionIntroduction•• ObjectivesObjectives•• Prior Art ReviewPrior Art Review•• SpecificationsSpecifications•• Design ConceptsDesign Concepts•• Design SelectionDesign Selection•• Future WorkFuture Work•• AcknowledgementsAcknowledgements

IntroductionIntroduction•• Long term space flights and the harsh spatial environments Long term space flights and the harsh spatial environments

pause several threats to the physical and mental health of pause several threats to the physical and mental health of astronauts.astronauts.

•• NASA continuously monitors the physiological parameters NASA continuously monitors the physiological parameters such as ECG,EMG, EEG, oxygen saturation in hemoglobin such as ECG,EMG, EEG, oxygen saturation in hemoglobin and variability of cardiac frequencyand variability of cardiac frequency

•• Variety of multiVariety of multi--parameter biomonitors have been introduced parameter biomonitors have been introduced in the past few years in the past few years

•• ProblemsProblems::−− Large sizeLarge size−− Heavy unitsHeavy units−− High power consumptionHigh power consumption−− Wires restrict mobility and could be a possible cause of noise.Wires restrict mobility and could be a possible cause of noise.

ObjectivesObjectivesThe goal of this project is to develop a biomonitor which wiThe goal of this project is to develop a biomonitor which will ll serve two primary objectives:serve two primary objectives:

•• To allow maximum ease of mobility by eliminating the need To allow maximum ease of mobility by eliminating the need for lead wires between subjects and physiological monitoring for lead wires between subjects and physiological monitoring unitunit

•• To develop a system readily adoptable by hospitals for any To develop a system readily adoptable by hospitals for any system used to monitor physiological parameters, notably system used to monitor physiological parameters, notably bedside ECG monitors. Development of such a system would bedside ECG monitors. Development of such a system would make transportation of patients fast and convenientmake transportation of patients fast and convenient

•• Additionally, our device could be used as a portable heart Additionally, our device could be used as a portable heart rate monitor with a LCD display on board. rate monitor with a LCD display on board.

Prior Art ReviewPrior Art Review

BIOMEDICAL WIRELESS AND AMBULATORY BIOMEDICAL WIRELESS AND AMBULATORY TELEMETRY FOR CREW HEALTH (TELEMETRY FOR CREW HEALTH (BioWatchBioWatch))

•• Manufactured by Zin MedicalManufactured by Zin Medical

•• WeightWeight: 155: 155--190 g190 g

•• SensorsSensors: EKG, EEG, EMG, EOG, : EKG, EEG, EMG, EOG, blood pressure and glucose, blood pressure and glucose, SPOSPO22, temp. and acceleration, temp. and acceleration

•• Sensor to monitor transmission:Sensor to monitor transmission: TelemetryTelemetryFigure 1. BioWatch Transmitter.Figure 1. BioWatch Transmitter.

Prior Art Review Prior Art Review contcont’’dd……....

AMBULATORY DATA ACQUISITION SYSTEM (ADAS)AMBULATORY DATA ACQUISITION SYSTEM (ADAS)

Figure 2. The Base Recorder of ADAS.Figure 2. The Base Recorder of ADAS.

•• Weight:Weight: 1 Kg1 Kg

•• Sensors:Sensors: EKG, EEG, EMG, EOG, EKG, EEG, EMG, EOG, blood pressure, heart rate and temp.blood pressure, heart rate and temp.

•• Composed of recorder base and Composed of recorder base and signal input modulesignal input module

•• Information saved and displayed Information saved and displayed on recorder baseon recorder base

•• Sensor to monitor transmission:Sensor to monitor transmission: TelemetryTelemetry

Prior Art Review Prior Art Review contcont’’dd……....

LIFE SYNC WIRELESS ECG SYSTEMLIFE SYNC WIRELESS ECG SYSTEM•• Manufactured by Life Sync Manufactured by Life Sync

CorporationCorporation

•• 2 units: patient transceiver (240 g2 units: patient transceiver (240 g ) and monitor transceiverand monitor transceiver

•• Receiver is connected to bedside Receiver is connected to bedside monitors to display ECG waveform monitors to display ECG waveform and measured dataand measured data

•• Sensor to monitor transmission:Sensor to monitor transmission:Wireless (BluetoothWireless (Bluetooth®®))

Figure 3. Life Sync Components Figure 3. Life Sync Components and as worn by patient.and as worn by patient.

Wireless ECG System: Wireless ECG System: Sensor UnitSensor Unit

Figure 4. Block diagram for sensor unit..Figure 4. Block diagram for sensor unit..

•• The proposed biomonitor system will serve as a stand alone ECG The proposed biomonitor system will serve as a stand alone ECG monitor and as a wireless adapter for existing bedside or monitor and as a wireless adapter for existing bedside or diagnostic ECG monitors and NASA biomonitors.diagnostic ECG monitors and NASA biomonitors.

•• The sensor unit consists of electrodes attached via short lead The sensor unit consists of electrodes attached via short lead wires to an acquisition circuit which amplifies and filters the wires to an acquisition circuit which amplifies and filters the acquired biopotentials and wirelessly transmits them to the acquired biopotentials and wirelessly transmits them to the receiver unit or PC.receiver unit or PC.

Specifications: Sensor UnitSpecifications: Sensor Unit

ParameterParameter RequiredRequired DesiredDesired

EMG, EMG, EEGEEG

100 dB100 dB

100 m100 m

RemarksRemarks

Measured Measured ParametersParameters

ECGECG Critical parameters indicative Critical parameters indicative of astronauts health status.of astronauts health status.

Signal to noise Signal to noise RatioRatio

60 dB60 dB The max. allowable noise in The max. allowable noise in the filtered signal will be the filtered signal will be < < 55µµV (before gain).V (before gain).

Wireless Wireless Transmission Transmission RangeRange

10 m10 m Sensor and receiver units Sensor and receiver units are not expected to be are not expected to be distant from one another in distant from one another in most setups.most setups.

Battery LifeBattery Life >> 8 Hrs8 Hrs >> 12 Hrs12 Hrs To reduce the need to To reduce the need to interrupt patient monitoring.interrupt patient monitoring.

Wireless ECG System: Wireless ECG System: Receiver Receiver UnitUnit

Figure 5. Block diagram for receiver.Figure 5. Block diagram for receiver.

•• The receiver unit displays measured data on an on board LCD. The receiver unit displays measured data on an on board LCD.

•• Receiver is connected (via telemetry) to existing ECG, EEG and Receiver is connected (via telemetry) to existing ECG, EEG and EMG monitors or biomonitors for waveform display.EMG monitors or biomonitors for waveform display.

•• Receiver will also be designed to wirelessly transmit informatioReceiver will also be designed to wirelessly transmit information n to PC.to PC.

Specifications: Receiver UnitSpecifications: Receiver Unit

ParameterParameter RequiredRequired DesiredDesired

Measured Measured ParametersParameters

ECGECG EMG, EEGEMG, EEG

DisplayDisplay Numerical LCDNumerical LCD Numerical & Numerical & Graphical LCDGraphical LCD

Battery LifeBattery Life >> 8 Hrs8 Hrs >> 12 Hrs12 Hrs

Battery Recharging Battery Recharging MethodMethod

USB OTGUSB OTG Solar CellsSolar Cells

WeightWeight < 960 g< 960 g < 400 g< 400 g

DimensionsDimensions < 32 x 50 x 12 cm< 32 x 50 x 12 cm < 8 x 12.5 x 3 cm< 8 x 12.5 x 3 cm

Design Concept # 1Design Concept # 1

Electrode 1Electrode 3

Electrode 2 + acquisition circuit

LED

Buzzer

BNC port

Lead ports

USB port

Num. LCDSensor Unit Receiver Unit

LED

Buzzer

BNC port

Leads ports

USB port

Num. LCD

Figure 6. Electrode strip with wireless transmitter.Figure 6. Electrode strip with wireless transmitter.

Design Concept # 2Design Concept # 2

3

2

Electrodes

Num. LCD

LED

BuzzerSensor Unit

Num. LCD

LED

BNC port

Lead ports

USB port

Buzzer

Receiver Unit

Figure 7. Wired electrodes connected to a wireless transmitter.Figure 7. Wired electrodes connected to a wireless transmitter.

Design Concept # 3Design Concept # 3

LED

Buzzer

BNC port

Lead ports

USB port

Num. LCD

Wireless Electrode 1

Wireless Electrode 2 Wireless Electrode 3

Sensor Unit

Receiver Unit

Figure 8. Stand alone electrode patches with individual wirelesFigure 8. Stand alone electrode patches with individual wireless transmitters.s transmitters.

Design SelectionDesign Selection

RejectedDesiredSelected

Wireless Trans. OptionsWireless Trans. OptionsWireless Wireless

Transmission Transmission MethodMethod

ProsPros ConsCons

ZigbeeZigbee

Wide transmission range: 100 m Wide transmission range: 100 m –– 1 1 milemileEnhanced freedom of movementEnhanced freedom of movementAllows monitoring of patients from a Allows monitoring of patients from a

distancedistance

Standard Zigbee transmission requires > Standard Zigbee transmission requires > 48V DC battery or AC power48V DC battery or AC powerNASA technical standards recommend NASA technical standards recommend

batteries of voltage batteries of voltage ≤≤ 30 volts (NASA 30 volts (NASA STDS 3000, Vol. I)STDS 3000, Vol. I)Relatively bulky size Relatively bulky size

BluetoothBluetooth

Direct Bluetooth transmission to PCDirect Bluetooth transmission to PCLow power consumption Low power consumption Longer battery lifeLonger battery lifeReduced noise and reduced sizeReduced noise and reduced sizeCan be powered with button cell Can be powered with button cell

batteriesbatteriesIntegral antennaeIntegral antennae

Short transmission range: 10 m Short transmission range: 10 m -- 100 m100 mRequires Requires ≥≥ 1212--bit resolution A/D and D/A bit resolution A/D and D/A

converters for accurate signalconverters for accurate signal

AnalogAnalog(FM, AM, PM(FM, AM, PM……) )

No A/D conversion required in the No A/D conversion required in the sensor unitsensor unitWider transmission range than Wider transmission range than

BluetoothBluetoothSensor unit readily adaptable to Sensor unit readily adaptable to

existing RF, FM and AM receivers existing RF, FM and AM receivers

Require external antennaRequire external antennaSignal affected by radio wave and Signal affected by radio wave and

electromagnetic interferenceselectromagnetic interferencesNoisier signalNoisier signalMay require filters in receiver to clean May require filters in receiver to clean

transmitted signal. transmitted signal.

Future WorkFuture WorkSensor UnitSensor Unit

Acquisition circuit PCB fabrication and components Assembly Acquisition circuit PCB fabrication and components Assembly •• CAD rendering of sensor unit casing.CAD rendering of sensor unit casing.

Wireless Transmission Wireless Transmission •• Testing of functional acquisition system with BluetoothTesting of functional acquisition system with Bluetooth®®

module (Free2Move, Inc).module (Free2Move, Inc).

Receiver UnitReceiver Unit•• Programming of Microcontroller (MSPProgramming of Microcontroller (MSP--430 by Texas 430 by Texas

Instruments, Inc) Instruments, Inc) •• Numeric LCD displayNumeric LCD display•• CAD rendering of casing.CAD rendering of casing.

MultiMulti--Parameters?Parameters?•• Extend scope of system to EEG and EMG.Extend scope of system to EEG and EMG.

AcknowledgmentsAcknowledgments

Coordinators:Coordinators:Prof. Marom Bikson, Ph. DProf. Marom Bikson, Ph. DProf. Luis Cardoso, Ph. DProf. Luis Cardoso, Ph. D

Teaching Assistant:Teaching Assistant:Gaurav Gaurav AgarwalAgarwal

Lab Coordinator:Lab Coordinator:Dr. Qiu Dr. Qiu Sponsor:Sponsor:

National Aeronautics and Space AdministrationNational Aeronautics and Space Administration