1. Group 16 Emily Jaeger Amy Rosenthal Nicole Typaldos

2.  Current weighing techniques are inadequate and often dangerous  Lifts require suspension of patient over the bed  Uncomfortable for patient and time consuming and difficult for nurses  Built-in scales have low accuracy (1% of patient weight)  Beds with built in scales are expensive, causing a low adoption rate

3.  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.

4.  The Bladder  Location of the weight sensing  The Controller  Allows the user to interact with the device and stores all important data  The Cart  Contains a pump and reservoir to fill, drain, and store the fluid when not in use

5.  Smallest bed deck size: 90.2 cm x 203.2 cm  Bladder dimensions selected to be 90 cm x 200 cm to accommodate all bed sizes  The bladder had to be thick enough to fit the sensor while also minimizing the volume of water  The internal thickness is 3 cm in order to accommodate the sensor

6.  Maximum weight to be held is 453.6 kg (1000 lb)  Given the area, this translates to a maximum internal pressure of 8.0 kPa

7.  Power Requirements for Each Component ComponentInput CurrentInput Voltage RangePower Range LCD Display 2mA5V10mW MCU10mA5V-6V500mW-600mW Pressure Sensors (4)8mA7V-8V56mW-64mW x (4) 16- Key Keypad1.8mA4.5V-5.5V8.1mW-9.9mW Fluid level sensor10mA5V50mW TOTAL792.1mW-925.9mW

8.  Pump Selection  Needed to be able to overcome the maximum pressure within the bladder to refill if patient is present  Needed to fill within our set goal of 5 minutes  To pump up to 53 L (14 gallons) in 5 minutes, or 2.8 gallons per minute minimum

9.  Material: PVC Tarpaulin (5 mm thick)  Dividers: High Density Polyurethane (HDPE) (2 mm thick)  Overall dimensions: 90 cm x 200 cm x 3 cm  4 compartments each with a pressure sensor

10.  Pressure to Weight  Each compartment contains a pressure sensor  The tare value of each sensor is stored in the controller  Using the area of the specific compartment, the weight on that compartment is obtained  These pressures are then summed by the controller to output the patient’s weight

11.  Internal Components  LCD Display  High contrast  Displays desired 40 characters  Minimizes glare in the hospital setting  MCU  Takes at least 10 inputs  Can store information and still obtain new information  16-key keypad  Numbers: 0 through 9  Function keys: Tare, Get weight, Adjust, Units, Cancel, Yes

12.  External Components  4 Pressure Sensors (140PC Series, Honeywell)  Gauge input  Linear within desired range  Fluid Level Sensor (eTape, Milone Technologies)  Varies resistance based on fluid level

13.  Cart Frame  Constructed from alloy 6061 aluminum  2.5” and 2.0” extruded square tubing (1/4” thick)  3/64” thick sheets for platforms  1.25” extruded circular tubing (1/16” thick)  Tiered design to minimize dimensions

14.  Water Reservoir  Material: HDPE (1/16” thick)  Volume  Maximum: 66.8 L  To fill line: 57.4 L  Opening near base with fitting for connection to pump  Design allows for higher fill accuracy as volume lowers

15.  The Pump  Rotary vane pump (McMaster-Carr)  19.7 L per minute (5.2 gallons per minute)  Maximum pressure of 1.66 Mpa (241 psi)

16.  Cords and tubing pose a tripping risk  High pressure produced by the pump, requires safety labeling and careful usage  Water spill risk due to the tubing  Controller displays warnings and confirmation screens when certain functions are called  Training required for nurses to ensure proper usage

17. ComponentQuantityUnit PriceTotal CostLead TimeSupplier PVC Tarpaulin (per square meter)2$15.00$30.0030 to 45 days CTA Hi-Tech Textiles Co.  In order to seal the bladder, high frequency welding is used.  Production cost ~$100

18. ComponentQuantityUnit PriceTotal CostLead TimeSupplier Keypad 16 key customize1$28.68 1 weekDigi Key LED display1$24.68 1 week Allied Electronics Control Panel Enclosure1$58.98 1 week OKW Enclosures, Inc Pressure Sensor4$127.75$511.00 1 week Jameco Inc. Keypad Encoder Chip1$5.19 1 week Jameco Inc. 3-PIN Sensor connector4$0.40$1.60 1 week Allied Electronics PCB circuit wiring black (100 ft roll)1$7.95 1 week Jameco Inc. PCB circuit wiring red (100 ft roll)1$7.95 1 week Jameco Inc. PCB circuit wiring white (100 ft roll)1$7.95 1 week Jameco Inc. 6-PIN Wiring connector1NA$8.90 1 week Allied Electronics 6-PIN Wiring connector recept1NA$8.90 1 week Allied Electronics AC-DC power supply1$11.86 1 week Digi Key Microcontroller Unit1$7.70 7 weeksDigi Key Printed Circuit Board1$30.58 2 weeksSunstone Circuits AMP Panel mount connectors/mate5$1.08$5.40 1 week Allied Electronics Card edge connector (connect keypad output to pcb)1$1.30 1 week Allied Electronics Total$728.62

19.  OKW provides free prototype creation with the purchase of controller housing products.  The PCB printing and customization would cost $30.58. (Sunstone Circuits)  Circuit assembly and soldering could be done by team members  For mass production  Circuitry assembly would cost $158  Milling of the enclosure would cost $14

20. ComponentQuantityUnit PriceTotal CostLead TimeSupplier HDPE (48" x 48")1$20.23 < 1 weekUS Plastics Corp Female Tank Fitting2$12.46$24.921 weekMcMaster-Carr Black Hose (per ft)12$1.20$14.401 weekMcMaster-Carr Hose Male Fittings (set of 2)2$16.68$33.361 weekMcMaster-Carr 24" eTape Continuous Liquid Level Sensor1$49.99 2 weeksMilone Technologies 12-24B-XD Wheel2$42.74$85.481 weekDarcor Casters 12-24-XD Wheel2$34.25$68.501 weekDarcor Casters 5/16" Square Bolts, 1" length (25 ct)1$5.59 1 weekMcMaster-Carr 2.5" Square Tube Aluminum, 1/4" thick (8 ft)1$97.34 1 to 2 weeksThe Metal Store 2.0" Square Tube Aluminum, 1/4" thick (6 ft)1$56.80 1 to 2 weeksThe Metal Store 1 1/4" Circular Tube Aluminum, 1/16" thick (8 ft)1$37.30 1 to 2 weeksThe Metal Store Rotary Vane Pump1$1,160.16 3 daysMcMaster-Carr Total$1,654.07

21.  Aluminum components are welded together  Rate of ~$60 per hour  For 2 hours of welding: $120  For prototyping, the tank is created through plastic welding of sheets of HDPE: ~$50 for fabrication  Mass production would utilize injection molding

22.  Total cost of materials: $2,412.69  Total cost of manufacturing: $300.58  Total cost for a single prototype: $2713.27

23.  Attempted to solve the problem, but many unforeseeable complications arose throughout the design process  Due to these complications, a patent was not pursued

24.  Communication and clear explanation is critical when working in a team  Even the smallest parts play a critical role  In preliminary design, all possible calculations, even trivial ones, should be completed to avoid surprises later on