Modular artificial beta-cell system: a prototype for clinical research

Eyal Dassau, Howard Zisser, Cesar C Palerm, Bruce A Buckingham, Lois Jovanovic, Francis J Doyle 3rd, Eyal Dassau, Howard Zisser, Cesar C Palerm, Bruce A Buckingham, Lois Jovanovic, Francis J Doyle 3rd

Abstract

Background: The quest toward an artificial beta-cell has been accelerating, propelled by recent technological advances in subcutaneous glucose sensors and insulin pumps. The development and clinical testing of algorithms involves several challenges: communication and data transfer between a sensor and a pump via computer, a human interface presenting real-time information to the physician, safety issues when an automated system is used to administer insulin, and an architecture that supports different sensors, pumps, and control algorithms. These challenges were addressed in the development of a modular artificial beta-cell system for clinical research.

Methods: The developmental environment of MATLAB (The MathWorks, Inc., Natick, MA) allowed the flexible implementation of communication protocols for different sensors and pumps. The system has a plug-and-play option for the control algorithm and a human interface that presents and logs the data, enforces protocol safety rules, and facilitates physician oversight.

Results: A novel platform for use in clinical research trials was realized as a bridge toward a portable unit. This prototype encapsulates communication between the control algorithm, the pump, and the sensors. Its intuitive human interface presents all the relevant patient information to the physician and allows events to be electronically logged. It facilitates subject safety by way of integrated interlocks, checklists, and alarms.

Conclusion: The modular design of the system allows for the robust testing of various sensors and pumps as well as feedback control, meal detection, predictive hypoglycemia alarms, and device-related algorithms to detect sensor or pump failure.

Keywords: artificial pancreas; closed-loop control; type 1 diabetes mellitus.

Figures

Figure 1.
Figure 1.
Schematic showing the components of the closed-loop system and identifying the communication links for each specific device. CSII is Continuous Subcutaneous Insulin Infusion; RF is Radio Frequency; PDM is Personal Diabetes Manager; RS-232 is a standard for serial binary data transfer; USB is Universal Serial Bus; and IrDA is Infrared Data Association.
Figure 2.
Figure 2.
APS layout showing the modularity concept. HMI denotes Human Machine Interface and APS is Artificial Pancreas Software.
Figure 3.
Figure 3.
Engineering overview of the software layout highlighting data transfer packages between modules and presenting the frequency of communication as well as the content of the package. APS denotes Artificial Pancreas Software; HPA is Hypoglycemia Prediction Algorithm; and RT is Real Time.
Figure 4.
Figure 4.
Activation interface realized in a simple and safe design.
Figure 5.
Figure 5.
Activation sequence that guarantees that the controller will only be enabled once all of the elements are running correctly.
Figure 6.
Figure 6.
FreeStyle Navigator® HMI.
Figure 7.
Figure 7.
DexCom STS7® receiver tool HMI presenting the last sensor reading with the appropriate data time stamp.
Figure 8.
Figure 8.
OmniPod® HMI displaying insulin infusion data 3.85 h into a trial.
Figure 9.
Figure 9.
Sample view of the APS HMI. The current and past data are represented including capillary BG measurements, glucose sensor readings (5 min interval), pump infusion rate, the current infusion rate, and the accumulated delivery.
Figure 10.
Figure 10.
Schematic showing implementation of MPC in the framework of the APS, where IOB is an insulin-on-board calculation.

Source: PubMed

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