Role of Modeling and Virtualization In Medical Device Development

• White Paper

solutions overview

Abstract

The medical devices and diagnostics industry is

increasingly adapting advances in information

technologies and systems for better diagnosis,

delivery of treatment, product lifecycle

management, new functionalities and features,

enhanced usability and product innovations to

reduce time-to-market. Software is playing a

major role in new features and functionalities

of devices, introducing an additional dimension

to the product development process. With an

increasing focus on regulatory compliance in light

of adverse incidents, these challenges can be more

effectively tackled by leveraging information

technologies. Modeling and simulation is one such

Advances in technology have enabled the

integration of mathematical models and

virtualization on a single platform. This platform

can be seen as a key enabler to reduce time

and cost while prototyping medical devices

and systems. Mathematical models that mimic

the functional behavior of a system have

found applications in various domains such as

process control and automotive, where these

models have been successfully deployed for

design, operational control and optimization

and diagnostic solutions. Recently, the medical

device industry has begun exploring the use of

models for new product introductions, improving

performance or reliability of existing designs

and overall re-engineering. Virtualization allows

the simulation of hardware components with

concurrent operating systems before actually

building the hardware prototype. Mathematical

models in conjunction with the simulated

hardware and applications forms the complete

system simulation.

This paper provides an overview of systems

modeling and its relevance to virtualized,

platform-based solution development. Such a

virtual platform allows device manufacturers

to use a range of simulation technologies with

which to test products for feasibility, design

sensitivity, performance, reliability, endurance,

safety and any other issues. A typical infusion

pump provides a good example to illustrate the

modeling paradigm and its applicability.

Overview

Medical device manufacturers make devices that

range from implants, to analyzer equipment,

pumps and dosing devices, sedation systems,

intelligent scanners and disposables used as

surgical aids. The challenge for medical device

manufacturers is to accelerate time-to-market

and stay lean on cost, without compromising

quality and regulatory norms. Their lifeline

depends on continuous improvisations and

innovations, leading to a stream of products

across segments. Additionally, there is a growing

need for adding electronics and intelligence

solutions overview 2

into devices. Such “electronic” medical devices

are becoming intricate due to multiple boards,

processors, operating systems and complex

decision making processes.

The typical product life cycle for a medical device

is shown in Figure 1.

The design phase covers stages such as ideation

and research, product design or prototyping, 1

2. The design phase, especially prototyping,

goes through various iterations, adding to both

cost and time. Functionality changes or design

alternatives means re-testing and validation,

hardware iterations. The absence of an interacting

environment limits the ability to achieve the

required functionality, which can be validated

during clinical trials only after the prototype

is developed. Compliance with regulatory

and effort, since the product and development

process itself is subject to scrutiny. Thus, to

perform hardware prototype testing for every

new product development cycle -- or to conduct

systematic analysis during re-engineering -- is

both costly and time consuming.

Modeling and Virtualization Paradigm

in addressing the needs of faster development

can be incorporated within model and software

simulations. Simulations comprise both the

functional behavior of the device or system and

the hardware components. The virtual platform-

based approach has three main elements.

Modeling that mimics the behavioral

functionality of the device and the interacting

systems.

Embedded hardware device simulation that

mimics the behavior of the target board

(CPU, memory, battery, etc.), enabling quick

The ability for models running on the

Windows platform to coexist and interact

with embedded target hardware simulators

and the functionality of the device running

on an embedded operating system on a

single PC.

The role of a virtualized platform in medical device

development is depicted in Figure 2.

Modeling involves the use of a mathematical

representation to describe a system. This can

be in the form of equations, data-driven models

or representations developed from domain

experts’ knowledge. Various techniques can be

used, such as CFD, parametric techniques, black-

box methods such as neural networks and other

A virtualized platform consists of a mix of virtualized

systems development (VSD) and virtualization.

VSD is product development without the use of,

or need of, the target hardware platform on which

the software will eventually run. With VSD, the

target hardware is simulated and runs on each

developer’s development workstation. For the

target software, the virtualized target hardware

Medical Devices Product Lifecycle

Ideation & Research Product

Design

Sustenance

PMA &510 (k)

Support

Testing &

Medical Device Product Life Cycle

Figure 1

Figure 2

SW – HMI, Hardware Model

Test Plan, Environment

Environment Model

Program

Quick design

savings

Virtual

thus fewer trials,

Environment Model

MonitorHardware

Model

Design

Develop

Run

Prototype Device

Clinical Trials

Hardware

industry-standard techniques

Develop the systems with the applicable IDE

Manufacture prototypes

Find only usability issues as

previous phase

Prepare for Study Environment

disparate OS, data sharing

behaves exactly the same as the physical target

hardware. The schematic representation of VSD

is shown in Figure 3.

Schematic VSD

Virtualization is a technology that allows the

concurrent running of two or more operating

systems on a single PC or embedded system, and

is being rapidly adopted in the engineering world.

It is enabled by a hypervisor, which is a software

layer that abstracts the hardware from the

operating system, permitting multiple operating

systems to run. A candidate representation of

virtualization is shown in Figure 4.

Representation of Virtualization

A virtualized platform allows for configurability

of design, enabling designers to iterate designs

quickly and develop a robust solution architecture

after considering all the possible alternatives in a

virtual manner. The simulations on a virtualized

platform help designers conduct what-if

analysis on various design aspects instead of

experimenting on developed hardware that could

be limited, underachieving and expensive.

Modeling medical devices or equipment can

be done mainly for new product development,

re-engineering or re-design. Such models can

learn from expert information or from an

experimental database. Models can be developed,

with appropriate fidelity, using tools such as

Matlab, Scilab, Mathematica, etc. The VSD

allows developers to define, develop, deploy and

integrate target-specific firmware, operating

system kernel and device drivers, and application

and communication stacks, even while the

hardware design and production progresses in

parallel, while virtualization allows them to save

costs, reduce footprint and consolidate systems.

The following section illustrates the use of

mathematical model and virtualization technology

for the design of a typical infusion pump. The

infusion pump is designed to provide a measured

flow of infusion fluid, medication or nutrients

to the patient. It has three major components:

the fluid reservoir, a mechanism such as a tube

for transferring the fluid to the patient and a

mechatronic system to generate and regulate flow.

The regulation of the drug concentration in the

body to achieve and maintain the desired result is

highly critical. An under-dosage may not provide

sufficient treatment, while an overdose can

produce dangerous side effects. The industry is

currently experiencing an increase in the number

and severity of infusion pump product recalls1.

solutions overview 3

Figure 3

Virtualized Target System with

Application

Application program and interfaces

Target operating system

Target hardware drivers and boot code

PC

Processors Memory Devices Network I/O

Figure 4

App1

Embedded OS

Hypervisor/Virtual Machine Monitor

Shared hardware

Another OS(Windows)

App1App1 App1

Advantages of VSD

• What-if analysis of various architectures and design• Identify problems early • Quicker detection and resolution of bugs• Highest quality assurance, early validation and

automated testing• Optimize hardware and software co-development to

produce higher quality systems in less time• Improve on time to market and overall saving in

development and deployment costs

On a broad level, Modeling serves as

• Enabler for new product development,• Platform for re-engineering and re-design. • Catalyst in choosing right-fit technology

alternative,• Tool to perform sensitivity analysis on various

design

Benefits of Virtualization

• Save Hardware cost and footprint• Make use of multi-core processors• Test beta systems and maintain legacy ap-

plications• Increase system security• Reduce time to market

This underlines the necessity of a platform to

experiment with and accelerate development.

Use of Modeling and Virtualization for Designing Infusion Pumps

The infusion pump is designed to provide

measured flow of infusion fluid, medication

or nutrients to the patient. It has three major

components, fluid reservoir, mechanism such as

tube for transferring the fluid to the patient and

mechatronic system to generate and regulate

flow. The regulation of the drug concentration

in the body to achieve and maintain a desired

result is highly critical. Underdose may not

provide sufficient treatment, while overdose can

produce side effects. Infusion pump in current

scenario is going through a phase where there

is rise in number and severity of product recalls

[1]. This underlines the necessity of a platform;

to experiment and accelerate the development.

The infusion pump is an intricate system

comprising mechanical, electrical and software

systems. A high-level schematic of a typical pump

is shown in Figure 5. The pump motor drives the

mechanism, including the gearbox and cam, to

achieve the required reciprocating action, such

as valves and/or shuttle mechanisms, that results

in the squeezing and unsqueezing of the tube.

This operation provides a positive displacement

of fluid, thus delivering the requisite fluid flow to

the patient. The accuracy of the output flow is

a critical performance parameter, and typically

there is no feedback available for it. The motor

controller is a hardware platform to which all the

sensors are interfaced, and it generates a control

signal for the motor operation. The power and

battery module manages the power supply for

the set-up.

High-Level Schematic of an Infusion Pump

The motor, and the associated drive mechanism

along with the tube, can be modeled using

tools such as Matlab. This detailed, high-fidelity

mathematical model helps in understanding the

interaction of the various subsystems, as well

as with optimizing overall system performance.

The motor controller and power and battery

target hardware are simulated on the virtualized

platform. The strategy and functionality code for

both is developed using a standard integrated

development environment and is integrated

into the virtual platform. The user interface

is developed on a platform for configuring

hardware and functionality parameters. Various

design alternatives can be tested by varying

these parameters. The mathematical model

developed in the Matlab environment runs on the

Windows OS and interfaces with the simulated

motor controller and power module through the

virtualized platform.

Virtualized Infusion Pump

Figure 6 shows the virtualized platform for

designing the infusion pump.

This virtualized platform offers the following

advantages.

� The opportunity to test different components

of the power module and motor controller.

� Mathematical models that enable design

sensitivity analysis, in the form of technology

change, material changes, etc.

� Testing of the end-to-end functionality of

the power module and motor controller.

� Minimal performance degradation from the

simulated hardware to the actual hardware.

� Ability to host various operating systems

that could be crucial from a functionality

perspective. For example, models can

solutions overview 4

Patient

Motor Controller

Power and Battery Module

Sensors(Temp, Pressure, Position etc.)

Drive Mechanism

Comprises gearbox, cam, valves, shuttle etc.

TubeAdministered

flow

Motor

Simulated hardware and functionalityMathematical model

Figure 5

Figure 6

Virtualized platform

User Interface

Data exchangeacross OS components

Configurator Display

Power module functionality

Power module Embedded OS

Power module hardware

Motor controllerfunctionality

Motor controller Embedded OS

Motor controller hardware

Behavioral functionality using

modeling tools

Windows OS

PC / Hardware

be executed on the Windows OS, as the

numerical methods or solvers are best

suited for such an operating system,

whereas hardware functionality needs a

real-time operating system.

Ability to perform data exchange between

disparate operating system applications.

Facilitation of experimentation, such as

Ability to more easily develop performance

analysis and test automation tools.

The Road Ahead

A number of things need to be addressed when

using a development platform for design at this

time.

Supporting various types of hardware

devices from different manufacturers.

time performance.

tested in real time.

Handling complexity issues due to

hierarchical scheduling as part of

virtualization.

Developing life cycle development tools for

analyzing performance, timing, memory,

code coverage and enabling test automation

for the virtual platform.

Conclusion

Modeling and virtualization together provide a

systematic integrated platform to accelerate the

can be expected across the ideation and research,

prototyping and sustenance stages, where models

can be exploited for system representations,

enhancements and re-engineering, while the

iterations in system prototyping can be reduced

through virtualization principles.

References

1. Total Product Life Cycle. FDA. www.fda.gov

2. National Instruments. www.ni.com

3. AJ5800 Volumetric Infusion Pump

operation manual.

4.

Baxter.

5. Wind River Systems Inc. www.windriver.com

6. Virtutech. www.virtutech.com

7. Eureka Infusion Pump operator’s manual by

Universal Medical Technologies.

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