Hybrid organic/inorganic nanostructures are engineered to function as two terminal devices with enhanced functionality. The devices are the building blocks for designing hybrid organic/inorganic circuits in the nanoscale. In our work, we have demonstrated the sensing capabilities of polymer nanocomposite thin films for designing nanoweb devices towards detection of biomolecules. Biomolecules with surface charge such as troponin-T were detected on this device by interfacing them with the polymer/metal composites. The change in electrical properties due to modulation in charge transport at the crossbar junction was identified as the measured electrical signal for designing switch based sensors. Nanotextured surface offers strong charge carrier transport and hence enhances the strength of the detected signal. The antibodyantigen interactions at the junction effectively modulate the charge transfer kinetics and modify the junction characteristics due to the surface potential associated with the organic molecules. The net change in surface charge can be measured either as changes in the diode current in the two terminal configuration or as changes in the source- drain current in the three terminal configuration. Detection sensitivity in the order of pg/mL was targeted by measuring the voltammetric current response (in microamperes).

This study demonstrates the development of a zinc oxide (ZnO) based microelectrode sensor for the ultra-sensitive detection of protein biomarkers. Our research focuses on utilizing a materials-based approach to achieve this objective by utilizing ZnO as part of our biosensor for (1) improved surface binding to enhance sensitivity and (2) creating a nanotextured surface for enhanced output signal response. Nanotextured ZnO thin films were integrated onto printed circuit boards using RF magnetron sputter deposition. Films sputtered with and without the presence of oxygen were examined for possible differences in biosensor efficacy. These fabrication conditions not only dictate the number of oxygen vacancies within the film but also regulate the amount of zinc and oxygen terminated ends occurring on the material surface. The correlation between the surface terminations of the nanotextured ZnO to its performance as a biosensor was evaluated using two cross-linker molecules, dithiobis succinimidyl propionate and (3-aminopropyl)triethoxysilane, that maintain different binding chemistries to ZnO. Qualitative and quantitative assessment of cross-linker binding was accomplished using fluorescent microscopy and fluorescent intensity measurements. Electrical impedance spectroscopy (EIS) was used as the transduction mechanism for detection of the well-established cardiac biomarker, troponin-T. Utilizing EIS with a functionalized immunoassay on the ZnO surface, troponin-T was detected as low as 10 fg/mL using ZnO films sputtered without oxygen. This enhanced detection of the cardiac biomarker can be directly attributed to 1) oxygen vacancies within the metal oxide film, 2) the nanotexturing of the sensing site surface, and 3) the ability to bind a significant amount of cross-linker molecules for immobilizing capture antibodies.

Here we introduce a cost-effective and highly sensitive flexible accelerometer system, which can sense human pulse by detecting the pulsation. The accelerometer employs capacitive sensing with a structure of two parallel plate electrodes with the optimally designed top electrode pattern in order to achieve high sensitivity. This flexible light-weight sensor is fabricated by direct-printing of silver nano-inks on pre-patterned flexible paper substrates. When the accelerometer is attached to the body surfaces: neck, inner elbow, or any other pulsation point, accurate pulse rates are obtained by reading out the voltage output signal.