Group 16 Members: Emily Jaeger, Amy Rosenthal and Nicole Typaldos Presented by: Nicole Typaldos

1. Progress Report PresentationSenior Design BME 401A New Minimally-Invasive Bedridden Patient Weighing System Group 16 Members: Emily Jaeger, Amy Rosenthal and Nicole Typaldos Presented by: Nicole Typaldos 29 October 2012

2. Brief Overview of Design • Weigh bedridden patients within 0.23 kg (0.5 lb) and with minimal movement of patient. • A single user with no additional training to operate the device and obtain patient weight in less than 5 minutes. • Device will not interfere with normal patient care. • Adult and obese patient weighing 22.7 kg to 453.6 kg (50 lb to 1000 lb) should remain comfortable. • Automatic readout to display screen. • The device will cost a maximum of $10,000.

3. Design Alternatives Above Patient Location breakdown of design alternatives Directly Under Patient Below Bed Deck Beneath Bed

4. Design Alternatives Under Consideration Four Scales under bed Two Slats under bed Lift mattress Single Fluid Filled Bladder Legs with load cells Capacitance load sensor Above bed deck four load cells Double lift device Measurement of string tension Spring partition mattress, displacement measurement Current inducing magnet mattress Compartmental fluid filled bladder

5. Above Patient • Double Lift Device • Alternative to a single patient lift device, device has two structures which connect above the patient’s bed to form a stable lifting apparatus. • Does involve displacement of the patient without repositioning. • Uses a typical sling lift, hydraulic lifts and attaching mechanism. • Wireless communication between the two sides. • Minimal tare capabilities.

6. Beneath Bed • Four Scales under bed • Improvement on currently available full bed weigh scales • Hospital bed is positioned on all four floor scales with patient remaining in bed • Compounding error unavoidable in this design • Use four load cells • Expanded force range to include bed weight, approximately 200 lb.

7. DirectlyUnder Patient Force Embodiment Fixed Plate with Dielectric Mobile Plate Support • Capacitance load sensor • Does allow patient to remain on device during entire stay. • Linear voltage output with respect to applied force. • Multiple measuring units necessary to acquire accurate readings. • Several variables to control design process to meet needs. • Unable to provide repeatability of readings in environment.

8. Analysis Performed To Chose Design • Research of current components available that would be needed in the device manufacturing. • Benefits and Compromises that would be necessary for each device. • Review of current patient care practices and procedures. • Review of each design for potential patient and nurse safety issues within the hospital setting. • Pugh Chart with 25 variables for comparison of each design alternative. • Focus on patient safety and meeting design specifications.

9. Chosen DesignCompartmental Fluid Filled Bladder • Several compartments that measure the absolute pressure within the fluid filled bladder. • Single compartment did not offer repeatability necessary for informative weights. • Number and distribution of compartments will be determined in next stage of design. • Device is able to withstand necessary force range while maintaining linearity. • Directly below the patient and mattress • Patient is weighed undisturbed. • Medical staff will have access to weight during patient stay.

10. General Design Single measurement unit Embodiment of Chosen Design Fluid Filled Bladder Hospital Bed Top Surface Base Surface Compartment Representation Pressure Sensor

11. Necessary Equations Absolute Pressure Weight of Patient where a= base area of bladder Compartment dimensions, solve to determine sensitivity to weight error, bladder fill conditions (h=height of bladder, A=total surface area, V=volume)

12. Schedule For Design Completion

13. Responsibilities • Emily Jaeger • Presentation of Final Design • Device embodiment design • Amy Rosenthal • AutoCAD and website design • Materials for Design • Nicole Typaldos • DesignSafe and contacting manufacturers • Program GUI for device

14. Questions?A New Minimally-Invasive Bedridden Patient Weighing System Group 16 Members: Emily Jaeger, Amy Rosenthal and Nicole Typaldos Presented by: Nicole Typaldos 29 October 2012