This thesis presents a novel architecture for a sensing element fabricated from a conducting polymer and a bioderived membrane. The thin film device provides controlled, selective ion transport from a chemical concentration and produces measurable electrical signals, ion storage, and small scale actuation. A chemical gradient applied across a bioderived membrane generates ion flow through protein transporters in the presence of a gating signal. A conducting polymer undergoes ion ingress/egress in the presence of an electrical and chemical potential, which causes a change on the polymers conformal backbone. A ligand (or) voltage gated protein in the bioderived membrane results in ion transport through the bioderived membrane. Integrating the two electroactive materials provides a unique architecture which takes advantage of their similarities in ionic function to produce a device with controlled and selective ion transport. The chemoelectromechanical device is one that couples chemical, electrical, and mechanical potentials through number of ions, dielectric displacement, and strain. The prototype consists of a stacked thin conducting polymer film and bioderived membrane which form three aqueous chambers of varying ionic concentrations. The top chamber contains an electrolytic solution, and the bottom chamber contains deionized water adjacent to the conducting polymer. The current that passes through a conducting polymer for an applied electrical signal is based on the level of doping/undoping and therefore can be used as a method of sensing protein function in the sensing element. This architecture results in a sensing element applicable in real time chemical sensors, volatile organic compound detectors, and bioanalytical sensors. The conducting polymer layer is formed from polypyrrole (PPy) doped with sodium dodecylbenzenesulfonate (NaDBS), and the bilayer lipid membrane is formed from 1,2-diphytanoyl-sn-glycero-3-phosphocholine (DPhPC) reconstituted with the protein alamethicin. The magnitude of current required to span a 175 µm pore was empirically found to be 326.5 A/cm2 and is based on electrode condition, electrode surface area, pyrrole concentration, and electrical potential. A micron-scale pore through a silicon substrate is spanned by a thin PPy(DBS) layer, forming a bridge which supports the bioderived membrane. The bioderived membrane is reconstituted with alamethicin, a voltage-gated protein extracted from trichoderma viride. Ion transport experiments were performed to characterize the PPy(DBS) layer and the bioderived membrane and are represented as electrical equivalents for subsequent analysis. The equivalent impedance of polypyrrole was calculated to be 1.7847±0.1735Ωcm2 and capacitance was calculated to be 1.2673±0.1823µF/cm2. The equivalent impedance of a bioderived membrane was calculated to be 1.654±1.9894MΩcm2, capacitance was calculated to be 1.1221± 0.239µF/cm2, and alamethicin resistance was calculated to be 1.025± 0.7228MΩcm2. Thus, using impedance measurements in the conducting polymer layer, it is proposed that a scaled up sensing element can be fabricated using the suspended polypyrrole supported bioderived membrane.

<p> Long-period fiber grating (LPG) sensors have been widely used as refractive index sensors due to their high sensitivity to the ambient refractive index change surrounding the fiber cladding of the LPG. Application of the LPG refractive index sensor has been found in chemical sensing and biochemical sensing, however for application of label-free dip and measure biosensors based on receptor immobilized LPG bio-sensor, the conventional fiber optic refractive index sensors are limited in the refractive index sensitivity, resolution, and operational range owing to the low sensitivity of the cladding mode effective index dependence on the ambient refractive index and the broad-spectrum feature of the LPG transmission spectrum. Low-cost, disposable fiber optic biochemical sensors with improved sensitivity, stability and resolution are needed to provide a high-sensitivity platform for immunology and DNA/aptamer biosensor. </p> <p> In this work, a novel fiber optic biosensing platform based on the LPG and the LPG in-fiber Michelson interferometer is designed and fabricated. The sensitivity and operation range enhancement is optimized by modifying the fiber cladding structure through reducing the cladding layer radius and applying a high-refractive index overlay with appropriate refractive index and thickness. The resolution of the refractive index sensor is improved by adopting the LPG in-fiber Michelson interferometer which turns the wide-spectrum feature of the LPG transmission spectrum into a narrow spectrum feature on the reflection spectrum of the interferometer. The reflection spectrum nature of the LPG in-fiber Michelson interferometer turns the sensor head into a single-end optotrode. The optotrode coated with bio-recognition film thus physically constitutes a short piece of fiber with one section of cladding reduced fiber. With single strand DNA (ssDNA) immobilized on the surface of the fiber cladding through biotin-avidin bridge, detection of the antisense DNA for the immobilized ssDNA is demonstrated. Immunoassay based on capture of target antigen by covalently immobilized antibody shows that reduction of the fiber cladding not only improve the sensitivity of the long period grating in-fiber Michelson interferometric biosensor but also improves the assay time. </p> / Thesis / Doctor of Philosophy (PhD)