1. External Enclosure

2. 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 and be comfortable for the user – The external package should resist minor splashing – The device should survive a fall from the hip Risks – Housing for the electronics is too heavy/large/uncomfortable – Water can enter the external package and harm the electronics – The housing fails before the electronic components in drop tests – The electronic components can not survive multiple drop tests

3. Concept Generation- Materials/Manufacturing Process Concept Generation- Material and Manufacturing Processes Manufacturing Processes Rapid Prototyping (ABS Plastic)StereolithographyInjection MoldedMachine Metal or Polymer Selection CriteriaWeightRatingNotesScoreRatingNotesScoreRatingNotesScoreRatingNotesScore Cost94 361 91$30k for mold92 18 Feasibility within timeline105 504long lead time401 103 30 Strength6437 MPa24558 MPa30535-70 MPa305~580 MPa30 Material Interaction with water42 84resin based165 204 16 Ease of Manufacturing35 155 3 93 9 0 0 0 0 20 wires0 10 wires0 3 wires0 0 Net Score 133 110 78 103 Rank 1 2 3 4 Continue? yes No no weight1- low importance 10- high importance rating1- does not meet cirteria 5- meets cirteria

4. Rapid Prototyping Machinable – Material can be drilled and tapped (carefully) Accepts CAD drawings – Complex geometries can be created easily – Ideal for proposed ergonomic shape Builds with support layer – Models can be built with working/moving hinges without having to worry about pins Capable of building thin geometries ABSplus – Industrial thermoplastic Lightweight - Specific gravity of 1.04 Porous – Does not address water resistant need http://www.dimensionprinting.com/

5. ABS Plastic Mechanical PropertyTest MethodImperialMetric 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 D7921.04 Coefficient of Thermal Expansion ASTM E8314.90E-5 in/in/F Important Notes Relatively high tensile strength Glass Transition well above body temperature Specific Gravity indicates lightweight material

6. Feasibility- Water Ingress Test 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 by examining water soluble paper 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 Preliminary Tests without protective coating show no traceable water ingress Spray on Rubberized CoatingLoctite

7. Feasibility- Robustness Testing Need: The device should survive a fall from the hip Specification: Drop Test – Drop external housing 3 times from 1.5 m, device should remain fully intact – Specify and build internal electrical components – Identify the “most vulnerable” electrical component(s) which may be susceptible to breaking upon a drop – Mimic those components using comparable (but inexpensive and replaceable) electrical components, solder on point to point soldering board 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 (proved unlikely with prototype enclosure) – The electronic components can not survive multiple drop tests Preventative Measures – Eliminate snap hinges from housing (tested and failed) – Test the housing first – Design a compact electronics package

8. Feasibility- Heat Dissipation of Internal Components 130°C is absolute maximum for chip junction temperature in order to function properly Goal- comfort for the user Assumed steady state, heat only dissipated through 3 external surfaces Maximum heat dissipation ~25W Actual heat dissipation ~5W t, k Q Tin Tout h

9. Prototype Enclosure Survived drop test Water resistant Plastic is machinable – Drilled, tapped, milled Helicoils should be used to tap holes – Constant opening and screwing and unscrewing of lid will result in stripped threads Approximate wall thickness (6mm) Distance between center of holes and wall needs to be increased – Some cracking occued Latches are not feasible

10. User Interface Components: Indication of battery life (3x LED) Indication of Fault (LED and Buzzer) Indication of levitation (LED) Display Increase/Decrease Speed (2x Button) Menu (Button) - - + + Speed Battery Life Fault Indication Speed Battery Life Fault Indication BATTERY OK ERROR MENU To Battery From Pump To/From Computer To Battery Connectors: 26- pin LEMO connector USB connector Battery Terminals (x2) OK: Indication of levitation ERROR: No Levitation, connection errors

11. User Interface- Components LED Backlit display with waterproof bezel and o-ring G/R/Y LEDs with O-ring and waterproof bezel Waterproof buttons with O-ring

12. User Interface- Connectors Current Model: Part # EGG 2K 326 CLL Proposed: Part # EEG 2K 326 CLV Pin Layout

13. User Interface- IP Codes IPIngress Protection First NumberProtection against Solid Objects 0- No protection (Sometimes X) 1- Protected against solid objects up to 50mm³ 2- Protected against solid objects up to 12mm³ 3- Protected against solid objects up to 2.5mm³ 4- Protected against solid objects up to 1mm³ 5- Protected against dust, limited ingress (no harmful deposit) 6- Totally protected against dust Second NumberProtection against liquids 0- No protection (Sometimes X) 1- Protection against vertically falling drops of water (e.g. condensation) 2- Protection against direct sprays of water up to 15 degrees from vertical 3- Protection against direct sprays of water up to 60 degrees from vertical 4- Protection against water sprayed from all directions - limited ingress permitted 5- Protected against low pressure jets of water from all directions - limited ingress permitted 6- Protected against low pressure jets of water, limited ingress permitted (e.g. ship deck) 7- Protected against the effect of immersion between 15cm and 1m 8- Protected against long periods of immersion under pressure DisplayIP 67 ButtonsIP 67 LEDsIP 67 USBIP 68 ConnectorIP 68