0:00:00 0:07:12 0:14:24 0:21:36 0:28:48 0:36:00 0:43:12 0:50:24 0:57:36 1:04:480

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colour change over time for large volumes of sample

[urea = 0.3mg/dl] [Urea = 1mg/dl] urine sample A

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Prototype for a Point of Care, Real Time Metabolic Sensor for ICU PatientsEjay Eze, Divine Nsoesie, Hartson Obasiolu, Rebecca Rubin, and Emmanuel Tito

Advisor(s): Professor Eisenstein, Professor Montas, Fischell Department of Bioengineering, University of Maryland / Dr. Avelino Verceles, University of Maryland, Baltimore

Capstone Group two would like to extend thanks to Dr. Yu Chen and Dr. Ian White, of the Fischell Department of Bioengineering at the University of Maryland, for their assistance with determining the short term optimal strategy for reading and processing optical density. We would also like to thank ASCO valves , a subsidiary of Emerson, for their donation of the pinch valves which were utilized in the project, and Worhtington Biochemical for their donation of the urease that was used in the project.

Fully integrate spectrophotometer and GUI with electronicsImplement automated washing stepImprove valve system so that not all urine is diverted Integrate a volume sensorMiniaturize device by utilizing higher quality valves or pumpsForm a start up companyPerform clinical experiments to precisely calibrate device values to disease statesApply for approval in the EUSell device to ICUs in the EUApply for FDA approval in the USSell device in USMake a nice presentation for Capstone class of 2045

•There were 4.4 million patients in the ICU in 2005, 90% of whom were on urinary catheters•In order to monitor kidney and digestive health, urine is collected for 24 hours, sent to a lab, and the results are then sent to a doctor to analyze with a pencil and paper.•This time lag allows disease states to progress, unnoticed and untreated for up to thirty hours•This device automates two tests- the urine urea nitrogen test and urine creatinine test, which provide insight into protein metabolism and kidney health. •Test results and basic analysis delivered every fifteen minutes.

Motivation

Electronics

Figure 1: Circuit design for control of the pinch valves. Five of the connections between the pinch valves and the Arduino are shown, the remaining four are identical.

Nine solenoid pinch valves are controlled by an Arduino Uno. Each pinch valve is damped by a resistor, a diode, and a transistor. The power supply was selected in order to deliver the 5A of current the pinch valves require.

Layout

Figure 3: Simplified flow diagram of the device, showing the path that urine takes through the device, and what happens in each chamber. Each arrow represents a pinch valve or a flow plate.

ChemistryTwo classic colorimetric reactions were used to quantify metabolic analytes. Urea yields a blue product using the Berthelot reaction, and creatinine yields an orange product using the Jaffe reaction. Chemistry was optimized for rapid and reproducible color development, minimum sample volume, and linearity for the standard curves throughout normal physiological ranges.

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f(x) = 1.10986363636364 x + 0.00504545454545446R² = 0.999860137956709

Urea nitrogen standard curve at 1:500 dilution of 5mg/ml stock solution.

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Figure 4: A)Chemical equation for Berthelot reaction. 2-2-dicarboxy indophenol is blue. B) Time course optimization for the reaction. The reaction is complete at five minutes for all concentrations of urea. C)Standard curve for Berthelot reaction. It is linear over normal, abnormal and nonphysical physiological ranges.

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f(x) = 8.05227272727273 x − 0.0050454545454546R² = 0.998432220645596

creatinine standard curve.

creatinine concentration, mg/ml

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Figure 6: A) Chemical equation for the Jaffe Reaction. B) Standard curve for the Jaffe Reaction in our set up. It is linear over normal and abnormal physiological ranges.

Future Work

Acknowledgements

Figure 2: CAD drawing of the divider of the device. Vials of reagents are placed in the notches shown, pinch valves are placed in the holes.