Defense Date


Document Type


Degree Name

Master of Science


Electrical & Computer Engineering

First Advisor

Vitaliy Avrutin

Second Advisor

Umit Ozgur

Third Advisor

Vamsi Yadavalli


Implantable or subcutaneous biosensors used for continuous health monitoring have a limited functional lifetime requiring frequent replacement and therefore may be highly discomforting to the patient and become costly. One possible solution to this problem is use of biosensor arrays where each individual reserve sensor can be activated on-demand when the previous one becomes inoperative due to biofouling or enzyme degradation. Each reserve biosensor in the array is housed in an individual Polydimethylsiloxane (PDMS) well and is protected from exposure to bodily fluids such as interstitial fluid ( ISF) by a thin-film nitrocellulose membrane. Controlled activation is achieved by decomposing over an individual sensor well. Electrically activated thermal decomposition of the nitrocellulose membrane is caused by passing an electric current through an Au/Ti filament placed on top of the membrane. By applying an energy of as low as 7 mJ to the Au/Ti filament with cross-sectional area of 8 x 107 cm2, a current density of ≈ 105 – 106 A/cm2 causes explosive decomposition of thin-film Au/Ti filaments. Having a thermal decomposition temperature of ≈200°C, nitrocellulose is locally heated directly under the Au/Ti filament. This leads to opening of the nitrocellulose membrane within 50 ms allowing for exposure of biosensor to biofluids. 50 ms is sufficiently short to prevent local heating of surrounding tissues and therefore is not a danger to a potential patient.


© Benjamin M Horstmann

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