Patient monitoring and Diagnostic Equipment Solutions

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Patient monitoring and Diagnostic Equipment Solutions. Medical Solutions. Introduction Purpose Introduce Intersil solutions for patient monitors and medical diagnostic equipment Objectives Overview of several sub-blocks of the patient monitor systems and various medical diagnostic equipment - PowerPoint PPT Presentation

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Patient monitoring and Diagnostic Equipment SolutionsSIMPLY SMARTER#1Medical SolutionsIntroductionPurposeIntroduce Intersil solutions for patient monitors and medical diagnostic equipmentObjectivesOverview of several sub-blocks of the patient monitor systems and various medical diagnostic equipmentPresent Intersil feature products with select application circuitsContent16 pagesLearning time30-40 minutes (estimated)

#Our purpose is to introduce Intersils solutions for patient monitors and medical diagnostic equipment. Were going to overview several of the sub-blocks from those systems and present Intersils feature products.2Patient Monitors High Level System

#A patient monitor is a medical device that has many biometric modules within it, like an ECG or EKG, pulse oximetry, blood pressure, body temperature, and respiratory sensing. There are many pieces to it and Intersil has parts that would fit in all of those red blocks. So dont forget the important blocks that could be hidden, that control an interface, the user interface display, and definitely the power.

3Intersil ProductsProducts HighlightedOp AmpsData ConvertersSwitches and MultiplexersRS-485/422 InterfacesVoltage referencesDigital Potentiometers (DCPs)Real Time ClocksPWM ControllersIntegrated FET Switching RegulatorsIsolated PowerBattery ChargersVoltage monitoring

Other Intersil ProductsAmbient Light Sensor/Proximity DetectorLED BacklightingAudio Amplifiers

#This is a list of the relevant product areas Intersil has today that play into the medical space. As you can see, there is a wide range of products from op amps to power management parts.

Here we will highlight the JFET low-noise op amps, the micropower precision op amps, the triple output PWM controller with LDO, the lithium ion switching charger, the power management IC (PMIC) and the low power switching regulator.4

ECG / EKGECG signals basicsTypically 0.05 Hz to 150 Hz bandwidth, 1mV to 10mV ppSystems are EMI sensitive Analog Frontend RequirementsLow noise at low frequency, high impedance (low leakage) components are requiredISL28110 for low noise, high impedance body probe buffersISL28217 for right leg driversOther analog components:ISL54500 for lead switchingISL21009D for low power VREFsAccuracy depends on AC or DC coupling approach from 10-bit to 16-bit.PowerMulti output voltage solutions for powering processors or FPGAISL9440A triple output controller and single LDO controller generates the rails for a FPGA.ISL80101 LDO family can reduce EMI in noise sensitive areas.

#5For ECG signals you have to be aware of two key components of the signal, ECG waveform and pacing artifacts. The ECG waveform is 0.05 Hz to 150 Hz bandwidth per medical standards. While the average R Wave Amplitude is 1.8mV, some waveforms can be as big as 10mVp-p. The pacing artifact require 2mV and 200s detection, while the average pulses are 1mV and 500s, but can be much smaller.

For the frontend of the body potential probes, typically high impedance buffers, or high impedance instrumentation amps, are used. They also need to have low voltage noise, and in many cases have to operate dual supply for best noise rejection and design. Intersils ISL28110 and ISL28210 are high performance JFET-input op amps ideal for high performance in these front ends.

For right leg drive, Intersils ISL28217 or ISL28233 are good solutions for their low power vs. low noise performance. While for post-gain/filter stages, Intersils ISL28414 low power op amps can be used. Typically the gain from the instrumentation amps thorough the gain/filter stages span from 1x to 50x for best signal-to-noise performance. We recommend Intersils iSim filter tool to building and selecting the right turnkey solution.

From a power management perspective there are a number of areas to be looked at. These systems are sensitive to EMI that can be introduced by the switching regulators, at the same time the portable systems need to be as efficient as possible, therefore they all need switching regulators. For processors, or FPGA power requirements, the ISL9440A is an ideal solution as it provides three switched rails but also has an on board LDO controller that can be used to clean up a rail if it is noise sensitive. This is a compact way to generate the Core, I/O and Aux rails for the processor in a very efficient manner. The ISL80101 family of high current LDOs can be used in the noise sensitive areas of the board where switching regulators would not be recommended. Blood Pressure (NiBP)- Non-Invasive Blood PressurePressure Sensor BasicsStrain Gauge, ROUT 5k, 0-300mm Hg Range, FSOUT= 300mV, BW = 5HzAnalog Frontend RequirementsLow noise and gain signal conditioning. Low noise at low frequency, high DC accuracy, low power vs. low noiseISL28217 or ISL28233 for low noise, high voltage for gain amplification (10x to 20x)Active Filters. Low pass filters for cuff pressure. Bandpass filters to capture oscillations, ISL28217 or ISL28233, use INTERSILS FILTER DESIGNER.See Intersils Medical Brochure for other analog components. http://www.intersil.com/literature/images/LC-097.pdfPowerFor portable monitors, efficiency and size are the main focus. ISL9440A, ISL9104, ISL8033 are some of the products that can power the FPGA and also work well to generate the power to the amplifiers in the system.

http://web.transim.com/iSimFilter/Pages/DesignReq.aspx

#6Now lets look at the technical basics of pressure sensors, like for a blood pressure module, before we look at the parts that would be best to recommend. Typically the pressure sensor is a strain gauge type with an output impedance of approximately 5kOhms with 300mV serving that 0 to 300mm Hg range. The typical bandwidth is 5Hz.

The analog frontend requires low noise and signal gain conditioning with typically 10x to 20x gain. This is followed by low pass filtering to capture the cuff pressure for low noise bandwidth limiting and a bandpass filter with gain to capture any oscillations and artifacts.

Again from a power perspective, the heart of the blood pressure monitor is the FPGA/Processor, and the best part to provide power to that device is the ISL9440A. However, more and more of these blood pressure monitors are becoming portable and with that the size of the processor is reducing. In these cases, the fully integrated switching regulators, like the ISL8033 or ISL85033, will generate two 3A rails from an input voltage range of 2.7V to 28V. For these applications, the key is efficiency and making the power solution compact.

Dont forget Intersils terrific iSim Filter Design Tools. http://web.transim.com/iSimFilter/Pages/DesignReq.aspx

SpO2 Pulse Oximetry(saturation oxygen in blood)Pulse Oximetry BasicsPulse Oximetry is the non-invasive measurement of the arterial bloods oxygen saturation.Detectors are needed to determine deoxygenated vs. oxygenated blood.Analog Frontend RequirementsDiagnostic SpO2 typically uses JFET-input op amps, or CMOS op amps are used to construct the transimpedance amplifier frontends.The ISL28110/210 is a precision JFET-input op amp that can be used for these applications because of its low noise and high impedance.PowerThe majority of these oximetry monitors are portable and run from 1 or 2 cell Li-ion batteries. These are rechargeable devices.The ISL9220A can be used in these applications to recharge at higher efficiency with up to 2A charge current.The ISL9104 fully integrated 500mA Switching regulator can be used to generate a very compact switching solution because of its high switching frequency.

#7SpO2 or Pulse Oximetry is the non-invasive measurement of the arterial bloods oxygen saturation.

The oximeter probe is comprised of two light emitting diodes, one red and one infrared, and a detector. (One reflects light from blood cells that are carrying oxygen and the other LED reflects from blood cells that arent carrying oxygen. That way the percentage of oxygen in the blood can be calculated.) In hospital diagnostic pulse oximetry, either precision JFET-input op amps, or CMOS op amps, are used to construct the transimpedance amplifier frontend. Some designs modulate the gain and dynamic range of these frontends, so amplifiers with wider operating voltages are required. The ISL28110/210 are precision JFET-input op amps that can be used for these applications because of their low noise and high impedance (low leakage, low bias current). Intersil is also developing other product options for amplifiers, so stay tuned for new releases.

The rest of the systems consist of converters and DSP used to take the DC and subtract the background noise. Proprietary algorithms exist from high-end to low-end pulse oximetry devices for hospital patient monitors to home use devices. Over-sampling, filtering and signal processing are needed to eliminate noise (i.e. movement artifacts).

The power section is interested in efficiency, size and ability to recharge. As these devices will run from Li-ion batteries the ability to recharge in a fast and efficient manner is very important. Size is another key element, as reducing the size of these portable devices is critical. Having switchers run at high switching frequencies allows the use of small external components while continuing to deliver in a very efficient solution. The ISL9220A is an ideal choice of switching charger that improves efficiency and speeds up charging of the batteries.Body TemperatureTemperature Sensor BasicsType varies for surgical, patient-care, home care. Typically either infrared, thermistor, or thermopile/ pyroelectric sensors.System consists of a small sensor voltage, then gain and filter signal conditioning.Analog Frontend RequirementsDiagnostic (professional) vs. home use (ear-type) vary. For diagnostic body temp monitors, use precision