Smart Sensor Systems for Invasive

Pressure Monitoring

Wilfried Mokwa

Institute of Materials in Electrical Engineering I (IWE I)

RWTH Aachen University, Germany

Sensor Systems for Invasive Pressure Monitoring

Wilfried Mokwa 2

intravascular

pressure bladder

pressure

gastric/intestinal

pressure

intraocular pressure intracranial pressure

Intracorporal Pressure Measurement

pressure in abdominal

aortic aneurysm

Sensor Systems for Invasive Pressure Monitoring

Wilfried Mokwa 3

Surface Micromachined Capacitive Pressure Sensor

A miniaturized plate capacitor for pressure measurement

-> miniaturization and low power consumption

Sensor Systems for Invasive Pressure Monitoring

Wilfried Mokwa 4

CMOS integration

• Integrated capacitive pressure sensor on

8“-wafer using surface micromachining

-> integrated single chip solution

Sensor Systems for Invasive Pressure Monitoring

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• Intracranial Pressure Measurement

• Intravasacular Pressure Monitoring System

• Conclusions

Intracorporal Pressure Measurement

Sensor Systems for Invasive Pressure Monitoring

Wilfried Mokwa 6

• Intra Cranial Pressure Measurement

• Intravasacular Pressure Monitoring System

• Conclusions

Intracorporal Pressure Measurement

Sensor Systems for Invasive Pressure Monitoring

Wilfried Mokwa 7

1 Cranium

2 Brain

3 Side ventricle

4 Third ventricle

5 Cerebrospinal fluid

6 Fourth ventricle

Anatomy of the Brain

Intracranial Pressure Measurement

Sensor Systems for Invasive Pressure Monitoring

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child with hydocephalus healthy child

ventrikular-peritoneale shunt

Intracranial Pressure Measurement

Sensor Systems for Invasive Pressure Monitoring

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ventricular-peritoneal shunt with externally adjustable valve

Christoph Miethke GmbH & Co. KG

Intracranial Pressure Measurement

Sensor Systems for Invasive Pressure Monitoring

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ventricular shunt with externally

adjustable valve and integrated

pressure measurement

HFDigital Part

EEPROMPressure Sensor

SensorReadout

Biasing &

Voltage Regulat.

Monolithically integrated capacitive

pressure sensors

Intracranial Pressure Measurement

Sensor Systems for Invasive Pressure Monitoring

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Telemetric read out system

Intracranial Pressure Measurement

Sensor Systems for Invasive Pressure Monitoring

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• Intra Cranial Pressure Measurement

• Intravasacular Pressure Monitoring System

• Conclusions

Intracorporal Pressure Measurement

Sensor Systems for Invasive Pressure Monitoring

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Intravascular monitoring system for hypertonia (HYPER-IMS)

• In Germany approximately 10

million people suffer from

hypertension (highly

increased blood pressure)

• About 10% of them have

problems to control their

blood pressure

• Approximately 10% of this

group are candidates for a

longterm-pressure-monitoring

Sensor Systems for Invasive Pressure Monitoring

Wilfried Mokwa 14

Arteria

Femoralis

Sensor tip

Implantable, wireless

long-term monitoring

system (24 hours / 7 days)

for:

blood pressure

heart frequency

blood pulse

cardiac rhythm

Subcutaneous transponder

Intravascular monitoring system for hypertonia (HYPER-IMS)

Sensor Systems for Invasive Pressure Monitoring

Wilfried Mokwa 15

ø 3 F ≈ 1 mm

Intravascular monitoring system for hypertonia (HYPER-IMS)

Sensor Systems for Invasive Pressure Monitoring

Wilfried Mokwa 16

Reference meassurement with Mammendorfer Sensor immediatily after implantation

55

60

65

70

75

80

85

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

time (sec)

blo

od

pre

ssu

re (

mm

Hg

)

HIMS 4614

MD-Sensor

System test

implantation of the sensor-tip into the arteria

femoralis of a sheap

subcutaneous placement of the transponder unit

acute and chronic in-vivo testing

Intravascular monitoring system for hypertonia (HYPER-IMS)

Sensor Systems for Invasive Pressure Monitoring

Wilfried Mokwa 17

• Intra Cranial Pressure Measurement

• Intravasacular Pressure Monitoring System

• Conclusions

Intracorporal Pressure Measurement

Sensor Systems for Invasive Pressure Monitoring

Wilfried Mokwa 18

Conclusions

By microsystem technology systems can strongly be miniaturized so

that implantation becomes possible

New applications will be possible (e.g. implants to measure and regulate

brain pressure as one example)

In future intelligent implants and protheses will support strongly the

field of "home care“

This work was partly funded by the German Ministry

of Education and Research

Long term stability of flexible “intelligent” implants

Further miniaturization

Energy harvesting

Assumption of cost by health insurances

Challenges