DARCI (Data Recording Instrument) is a clinical data collection and research quality assurance tool designed and built by Champlin Technologies LLC for Seattle Children’s Research Institute (SCRI). DARCI measures differential pressure of air from -5 to 30 cm-H2O on its inlet port (Luer lock taper fitting) with a resolution of 0.05 cm-H2O at 125 samples/second. DARCI has internal non-volatile memory for storing up to 120 days of continuously collected data. Through a USB virtual com port, a Windows program configures DARCI and downloads recorded data. The DARCI enclosure measures 4.5 x 3.5 x 3.5 inches (LWH) with a standard ISO19054 pole mount fitting attached on the back. A medical-grade plug-in AC transformer provides electrical power (5 Vdc) to DARCI. An internal battery and on-board non-volatile memory provide continuous recording and storage of data for up to 24 hours in the event of an AC power interruption or loss. A start button with a green LED and a stop button with a red LED provide the operational interface to the user or medical staff. Except for a small pressurization vent hole, the lid interface and all connectors and switches are sealed and installed with gaskets to support wipe-down.
DARCI has been used successfully during SCRI’s studies of its Seattle-PAP. For each of the premature infants enrolled in the latest study, one DARCI unit measured air pressure in the esophageal catheter (Pes) and a second unit measured air pressure at the patient airway/nasal interface (Paw). DARCI recorded air pressure data on internal memory for download and analysis. DARCI performed reliably and consistently throughout the various studies.
DARCI functionality is provided by two main components:
All of the internal electronic circuitry resides on a single two-layer circuit board measuring approximately 10 x 7 cm. Schematic capture and circuit board layout were created in Altium Designer. The bare PCB was fabricated by Sunstone Circuits located in Mulino Oregon.
Printed Circuits Assembly (PCA)
The electronics parts were assembled onto the PCB by Printed Circuits Assembly (PCA) Corporation located in Bellevue WA. The 8-pin empty pad is the location for the Honeywell HSCMRRN001PD2A3 pressure sensor. Because of their potential sensitivity to the automated assembly processes, these parts were hand-soldered to the PCB.
Plastic Sales and Service Inc
The enclosure that houses DARCI is made of moulded high-impact ABS material. The LID and base incorporate a tongue and groove seal using a neoprene gasket. The lid is attached with four screws located outside the sealing area to avoid ingress of moisture and dust. A thermal screen process was used to fuse the ink into the ABS material keeping the surface smooth. Plastic Sales and Service Inc., located in Seattle WA, did the high-quality labeling on the lids.
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