Invivo Device for Measuring and Adjusting LapBand Pressure
In-vivo Device for Measuring and Adjusting Lap-Band Pressure ©Bill Watterson John Huidekoper Mark Fritz Chris Schroeder Andrew Koivuniemi David Mayhew Advisors: Dr. Robert Roselli Dr. Thomas Rauth
Background Information n n Obesity in United States Sources of help ¡ ¡ Gastric Bypass Lap-Band Source: http: //www. sptimes. com/2003/10/14/Worldandnation/Number_of__extremely_. shtml
Reasons for Design Choices n Problems ¡ Device Failure n n ¡ n Leaks (Maude Database) Patient Pain No Constant Pressure Fixes ¡ ¡ Implantable Pump Autonomous Control as well as Non-Invasive Control
Ideas we’ve tossed out n External control ¡ ¡ Still have problems with the port Patients could unhook the device if uncomfortable = defeating the purpose http: //www. minimed. com/images/x 22_features_callout. jpg
Ideas we’ve tossed out n Syringe pump ¡ ¡ ¡ http: //www. klf-insurance. com/images_for_site/syringe. jpg Dead space behind it No mechanical advantage The ones out there are too large for implantation
Basis of our ideas n n n Car-jack Pacemaker Squeezing on fluid bag http: //www. 3 dkingdom. org/modules/My_e. Gallery/ gallery/models/thumb/Car. Jack. Model. jpg http: //www. syncope. co. uk/images/Pacemaker. JPG
Current Pump Design
Torque Considerations
Current Pump Design
Motors n Stepper motors ¡ ¡ ¡ Provides fine tuning in angular position Good with microcontroller Provides detent torque
Motor Selected n n n Micromo AM 2224 This is a stepper motor Allows for specific positioning and micro control 23 mm diameter 4 cm long Max Torque
Gearing n Advantages ¡ ¡ n Disadvantage ¡ ¡ n n Increased Torque Increased Precision Occupies Space Less Efficient Tried to make our own Problem- Small Gears are very expensive
Our Gears n Gearhead ¡ ¡ ¡ Attaches to the front of the motor Increases the torque several orders of magnitude (1000: 1) Does increase motor length to 7 cm
Necessity of Pump Control Pressure Adjustment Desired Curve Loss of Pressure
RF Control Chip Negative Feedback Control - Pressure Drop in Lap-Band Pressure Transducer Detects Changes Pump Changes Volume Of Saline in Lap-Band Data Processing of Multiple Readings Chip Determines Necessary Volume
Bag to Hold Saline Exploring several options: 1) Bag Material 2) Bag Fabrication Saline-Filled Bag Prototype Pump -Easily disassembled -Experiment with bag designs
Progress Summary n n n Pump Design Pump Fabrication Electronics (Chip, Pressure Transducer, Battery, Motor Control) Bag Design/Fabrication NCIIA Grant
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