Towards a Bioartificial Kidney:Validating Nanoporous Filtration Membranes

Jacob Bumpus, BME/EE 2014Casey Fitzgerald, BME 2014Michael Schultis, BME/EE 2014

Clinical Relevance• 600,000 patients were treated for end stage renal disease (ESRD) in the

US alone in 2010

• Current treatment procedures include kidney transplant and routine dialysis

• Dialysis is costly, averaging approximately $65,000/patient annually and time consuming, in many cases requiring thrice weekly treatment

• Significant shortage of donor organs for transplant means that many patients are left with no options other than years of routine dialysis

Clinical Relevance• Development of an artificial, implantable kidney would revolutionize

treatment of end stage renal disease (ESRD).•Improve patient outcomes•Reduce economic burden of treatment

• Dr. Fissell is working to develop an implantable bioartificial kidney using nanoporous silicon membranes as biological filters

Problem Statement• The Fissell lab must manually configure filtration experiments, monitor

them continuously throughout their duration (sometimes days to weeks long), and collect data by hand

• Current experiments are unable to simulate physiologically relevant fluid flow profiles, and are limited to constant flow rates

• No failsafes exist in order to protect the silicon membranes from being damaged in the event of deviations from preset conditions

Primary ObjectiveA robust testing and characterization platform is needed to streamline verification of these nanoporous filtration membranes. Our primary objective is to develop an elegant, dynamic hardware control system that maximizes experiment control and precision while minimizing user involvement during filtration experiments for the verification of nanoporous silicon membranes.

Goals• Experimental setups should be fully automated, permitting the lab

technician to begin the experiments and then cease involvement except for occasional system monitoring

• Allow user-defined hardware setup so that numerous different experiments can be run from the same system and is modular and expandable

• An intuitive graphical user interface (GUI) should be developed in order to allow the user to control multiple experiments effectively and efficiently so that setting the experiment parameters is secondary to deciding what the parameters should be

• Add flow rate control and dialysate measurement to the current pressure control feedback system

Solution Description• The solution must automate three modes of experimentation• Hydraulic Permeability Mode• Measures convective flow across membrane at various pressures

(uL/min/psi)• Filtration Mode• Collect filtrate samples at various pressures for further analysis

• Dialysis Mode• Sets and Measures diffusive flow across membrane with no pressure

differential• Each mode should include an option to run with constant flow or a

periodic waveform

Factors• Software Platform

•LabVIEW--> more $ / much less development time

• Software concurrency•More-->fewer programs running / internals are more complex

• Hardware connections•Fewer--> smaller size and $ / more technically challenging

Performance Criteria• The final design iteration should be implemented by April 21st

• The system should require minimal user involvement (<5min setup, <10min/day monitoring)

• Pressure and Flow throughout the close system must be regulated (+/-20%) to include:

• Fail-safes that protect nanoporous silicon chips from breaking (due to pressure spikes)

• Flow profiles that mimic physiological waveforms (pulsatile flow)• Data must be automatically acquired and saved periodically• The completed system will be designed so that an individual with limited

experience can easily and quickly learn to run these complex experimental protocols

System and Environment

System and Environment

Control Box Concept

Graphical User Interface (GUI)

Graphical User Interface (GUI)

G Code

ConclusionsThe following components and software utilities are shown to be interoperable, indicating strong technical feasibility of project goals:• pressure transducer control & communication• pressure regulator control & communication+ LabVIEW PID feedback loop for

pressure setup• improved/updated circuitry• LabVIEW control of peristaltic pumps

•leading to initial tests of pulsatile flow• serial communication to mass balance• This is further supported in our abstract submission to American Society for

Artificial Internal Organs (ASAIO) Student Design Competition

Informal Observations• We can currently control the pressure within the filtration system to

within .02 psi of the desired set point

• Pulsatile waveforms seem feasible within our design constraints and requirements, which would confer greater physiological relevance to current verification methods

• The next steps in the project are to include syringe pump control and mass balance control within LabVIEW

Gantt Chart

Questions?