WIRELESS IMPLANTABLE

SENSOR PLATFORM

Introduction

It’s a part of an electronic prototype that operate in MICS band

Used to transfer information's regarding the patient during and after the surgery

It has an implantable platform and an external base station

It has a communication range of 2m

Block Diagram

Sensor Platform•Main Components:

A wireless transceiverMicrocontrollerCapacitive power moduleAntenna

TransceiverZL70101Designed for medical applicationsLow power consumptionHigh data rate up to 800 Kb/sec

MicrocontrollerMSP430F2132Small sizeLow power consumption10 bit A-D converterIn built temperature sensorUsed to configure wireless transceiver

and respond to user commands

Power module and Antenna

Stored energy in 3 parallel 220mF EDLC

Antenna used is printed circuit board antenna

Base StationMain Components:

2.45GHz transmitterA wireless TransceiverMicrocontroller (MSP430F1611)Antenna

How It Works?The sensor platform operates in two

modes a sleep mode and an active modeThe communication is initialized by

transmitting an ook wake up signal via 2.45 GHz transmitter

Communication in MICS band in half duplex communication link

The sensor platform sends response packets after receiving a request from the base station

Functionality TestsTemperature sensor accuracy

Power Consumption

Communication range

Temperature sensor accuracy

The internal sensor is compared with an external sensor

A thermocouple is taken as reference

All are subjected to temperature variations

Measurements are taken at intervals

Result

Communication RangeThe sensor platform is placed at increasing

distance from the base station

The base station tries to initiate and maintain wireless link each time

Number of successful connections were noted

Result• 100% reliable in

the targeted range

92% reliable in 2-6 m

Power Consumption The average power consumption of the

sensor platform is measured in two modes

Multimeter measures supply current at 3v

Averaged it over a period of 10 minutes in both the modes

ResultIn sleep mode sensor platform drew an

average current of .128 mA resulting in .654mW power consumption

In active mode current drawn was

5.194mA resulting in 15.582mW power consumption

Advantages

Reduced risk of interferencesLow power consumptionSmall size

ApplicationsMainly used in scoliosis correction

Used in medical applications

ConclusionWith the advancement in wireless

technology it is possible to operate wireless implants for longer period.

The designed prototype is found to be efficient and has reduced the risk of scoliosis surgery.

ReferencesBase Paper: “Wireless implantable sensor platform ” Daniel

Zbinden, Edmond Lou, Nelson Durdle,2010 IEEE.Y.Cortel , J Dubousset and m.Guillaumat, “New universal

Instrumentation in spinal surgery ”, Clin Orthop;vol.227E. Lou, V.J.Raso, B Martin,E.Epper and D.L.Hill,” A wireless load

measurement tool for spine surgery,”D. Benfield, E.Lou, W Moussa. ”Development of a MEMS based

sensor array to characterize in situ loads during scoliosis correction surgery”

www.zarlink.com/zarlink/zl70101-productwww.focus.ti.com/docs/prod/msp430f2132www.elna.co.jp/en/capacitive/dsk

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