Smiha Sayal

 Left Ventricular Assist Device (LVAD)  Mechanical device that helps pump blood from the heart to the rest of the body.  Implanted in patients with heart diseases or poor heart function.

 Miniaturize the existing LVAD system to achieve portability while retaining its safety and reliability.

All team members

 Safe  Robust  Affordable  Easy to wear and use  Interactive with user  Controllable by skilled technician  Comparable performance  Compatible with existing pump

CorAide (NASA)

 “Black box” architecture used during development  Large, not portable  Runs on AC power

 Has both internal / external components  Equivalent to our “Option 2”  Unfinished implementation

All electronics external

ADC internal only

Pump and motor control internal

All electronics and battery internal

Option 1 Smallest internal volume Feasible within timeline Easiest to maintain Minimum 20 wires Option 2 Relatively small internal volume Slightly higher risk of internal failure Minimum 10 wires Option 3 Large internal volume Difficult to design Electronics failure is fatal Minimum 3 wires Option 4 Large internal volume Difficult to design Electronics failure is fatal Minimum 3 wires Best Option

Nicole Varble and Jason Walzer

 Needs  The external package should be lightweight/ robust/ water resistant  The devices should be competitive with current devices  The device should fit into a small pouch and be comfortable for user  Specification  Optimum weight of 5 lbs  Optimum dimensions of ~6” x 2” x 2”  Risks  Housing for the electronics is too heavy/large/uncomfortable  Preventative measures  Eliminate heavy weight materials  Eliminate weak, flexible materials  Material is ideally machinable

+Extremely lightweight -Not robust -Long machining and processing time External mold to create silicon/plastic housing +Extremely lightweight +Relatively robust +Extremely fast machining time Rapid Prototyping +Lightweight +Robust -long machining and processing time Aluminum housing +Relatively lightweight +Extremely robust -long machining and processing time Titanium housing

 Dimension System  ABSplus  Industrial thermoplastic  Typically used for product development  Machinable  Material can be dilled (carefully) and tapped  Accepts CAD drawings  Obscure geometries can be created easily  Ideal for proposed ergonomic shape  Lightweight  Specific gravity of 1.04  Porous  Does not address water resistant need  0.007” material/layer  Capable of building thin geometries  Builds with support layer  Models can be built with working/moving hinges without having to worry about pins

Mechanical Property Test Method ImperialMetric Tensile StrengthASTM D6385,300 psi37 MPa Tensile ModulusASTM D638330,000 psi2,320 MPa Tensile ElongationASTM D6383% Heat DeflectionASTM D648204°F96°C Glass TransitionDMA (SSYS)226°F108°C Specific GravityASTM D Coefficient of Thermal Expansion ASTM E E-5 in/in/F Important Notes Relatively high tensile strength Glass Transition well above body temperature Specific Gravity indicates lightweight material

 Need: The external package should resist minor splashing  Specification: Water Ingress Tests  Once model is constructed, (user interface, connectors sealed, lid in place) exclude internal electronics and perform test  Monitor flow rate (length of time and volume) of water  Asses the quality to which water is prevented from entering case  Risk: Water can enter the external package and harm the electronics  Preventative measures:  Spray on Rubber Coating or adhesive  O-rings around each screw well and around the lid  Loctite at connectors

 Need: The device should survive a fall from the hip  Specification: Drop Test  Drop external housing 3-5 times from hip height, device should remain fully intact  Specify and build internal electrical components  Identify the “most venerable” electrical component(s) which may be susceptible to breaking upon a drop  Mimic those components using comparable (but inexpensive and replaceable) electrical components  Goal  Show the housing will not fail  Show electronics package will not fail, when subjected to multiple drop tests  Risks  The housing fails before the electronic components in drop tests  The electronic components can not survive multiple drop tests  Preventative Measures  Eliminate snap hinges from housing (screw wells to secure lid)  Test the housing first  Take careful consideration when developing a thickness of the geometry  Design a “tight” electronics package

 Need: Internal Enclosure dissipates a safe amount of heat to the body  Risk: Internal electronics emit unsafe amounts of heat to body  Benchmarking:  Series of tests studied constant power density heat sources related to artificial hearts  60-mW sources altered surface temperatures 4.5, 3.4, 1.8 °C above normal at 2, 4, 7 weeks  40mW/cm 2 source increased to upper limit of 1.8 °C  Specifications: Internal devices must not increase surrounding tissue by more than 2°C Wolf, Patrick D. "Thermal Considerations for the Design of an Implanted Cortical Brain–Machine Interface (BMI)." Ncib.gov. National Center for Biotechnology Information, Web. 30 Sept

 Need: Device should be comfortable for user  ANSUR Database  Exhaustive military database outlining body dimensions  Waist Circumference (114)  Males: mm  Females: mm  Waist Depth (115)  Males: mm  Females: 102 mm  Calculated average radius of hip  Males: mm  Females: mm  Acceptable Avg. Radius of hip  ~120 mm

 CAD model is can be easily resized  Removable top panel for electronics access

Andrew Hoag and Zack Shivers

 Requirements  Selecting suitable embedded control system  Designing port of control logic to embedded system architecture  Customer Needs  Device is compatible with current LVAD  Device is portable/small  Allows debug access

 Impeller must be levitating or “floating”  Electromagnets control force exerted on impeller  Keeps impeller stabilized in the center  Position error measured by Hall Effect sensors

 Algorithm complexity influences microcontroller choice  Electronics choices affect volume / weight  Proportional – Integral – Derivative (PID)  Very common, low complexity control scheme

 Requirements:  Can handle PID calculations  Has at least 8x 12-bit ADC for sensors at 2000 samples/sec  Multiple PWM outputs to motor controller(s)  Same control logic as current LVAD system  Reprogrammable

 Custom Embedded  dsPIC Microcontroller ▪ Blocks for Simulink ▪ Small ▪ Inexpensive (<$10 a piece)  TI MSP430 ▪ Inexpensive (<$8 a piece) ▪ Small, low power  COTS Embedded  National Instruments Embedded ▪ Uses LabVIEW ▪ Manufacturer of current test and data acquisition system in “Big Black Box” ▪ Large to very large ▪ Very expensive (>$2000)

 Closed-loop feedback control using PID – currently modeled in Simulink for use with the in “Big Black Box”  Additional microcontroller-specific software will be required to configure and use A/D, interrupts, timers.

 Not at subsystem level detail yet.  Life-critical operations would run on main microcontroller.  User-interface operations run on separate microcontroller.  Possible LRU (Least Replaceable Unit) scheme

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