Continuous Glucose Monitoring(CGM) Biosensor

Rana Muhammad Umer

ECE 6200

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OUTLINE

• Introduction• Motivation• Principle & Design• Fabrication Steps• Conclusion

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Introduction

• Fully Implantable Device• Capacitive based sensor• Monitors Glucose level in Blood• Real-time Monitoring• No Moving Part• Dielectric Affinity Detection

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Introduction

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Motivation

• A Fully Implantable Device

• Monitors Glucose Level in Real Time

• No Mechanically Moving Parts

• No Intricate Actuator Design

• Less susceptible human and environmental disturbances

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Principle & Design

• Detects glucose-induced permittivity changes of solution of glucose sensitive polymer.

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Principle & Design

• Two Electrodes: Upper Perforated Electrode & Lower Electrode on Substrate

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Principle & Design

• Diaphragm is supported by anti-stiction posts to avoid collapsing and providing mechanical stability.

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Principle & Design

• Semi-permeable membrane to restrict polymer in u-chamber and allow only glucose to transverse.

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Principle & Design

• The solution between two electrodes acts as the dielectric material for capacitive detection.

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Fabrication Steps

1- Deposition of Gold on Si substrate for bottom electrode.

2- Deposition of Parylene passivation layer through chemical vapor deposition(CVD).

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Fabrication Steps

3- Deposition of thick sacrificial photoresist layer.

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Fabrication Steps

4- Deposition of second Parylene layer.

5- Gold layer deposited and patterned to form perforated upper electrode.

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Fabrication Steps

6- Deposition of another Parylene passivation layer on top of upper electrode.

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Fabrication Steps

7- Patterning of SU-8 reinforcement layer to form nine anti-stiction posts.

8- SU-8 spin coated to form micro-chamber.

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Fabrication Steps

9- Using SU-8 as mask Parylene layers are patterned and sacrificial layer is etched using Reactive Ion Etching.

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Fabrication Steps

10- Cellulose semi-permeable membrane is glued in the last on the top of micro-chambers using epoxy.

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Conclusion CGM biosensor uses real-time monitoring dielectric detection to monitor

the level of glucose in blood.

Affinity binding between glucose and polymer( PAA-ran-PAAPBA) results in a decrease in permittivity of solution.

Decrease in permittivity is detected by two electrodes.

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References

[1] Xian Huang, Siqi Li, Erin Davis, Dachao Li, Qian Wang, Qiao Lin; ‘A MEMS Dielectric Affinity Glucose Biosensor”; Journal of Microelectromechanical Systems, February 2014.

[2] A. Heller, “Implanted electrochemical glucose sensors for the managementof diabetes,” Annu. Rev. Biomed. Eng

[3] Y. Zhao, S. Li, A. Davidson, B. Yang, Q. Wang, and Q. Lin, “A MEMS viscometric sensor for continuous glucose monitoring,” J. Micromech. Microeng

[4] X. Huang, S. Li, J. S. Schultz, Q. Wang, and Q. Lin, “A dielectric affinity microbiosensor,” Appl. Phys. Lett.

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