Jeffrey B. Mecham

Novel ductile polyaniline/sulfonated poly(arylene ether sulfone) composites

Thermally stable, ductile, and electrically conductive composite films made from sulfonated poly(arylene ether sulfone) (BPS) and polyaniline emeraldine base (PANI) were prepared. Tensile tests were conducted for both dry and fully hydrated composite films, and the BPS copolymer. The composite films were as ductile and tough as the neat supportive matrix with up to 20 wt% PANI loading. Thermogravimetric analysis indicated that the 20 wt% PANI-containing composite films had better thermal stability than the unfilled BPSH supportive matrix, which reinforced the PANI quite well.

Electrically conductive polyaniline-sulfonated poly(arylene ether sulfone) composites

Electrically conductive composite films from sulfonated poly(arylene ether sulfone) and polyaniline emeraldine base were prepared. The electrical conductivity values, which would be useful for a wide range of applications, were achieved after only 1min of doping in protonic acid solution. A molecular interaction between the supportive matrix and conductive filler is inferred based on significant difference in the Fourier-transform infrared spectra of the doped and undoped composite films.

Optical fiber sensor for breathing diagnostics

We report improvements of an optical fiber-based humidity sensor to the problem of breathing diagnostics. The sensor is fabricated by molecularly self-assembling selected polymers and functionalized inorganic nanoclusters into multilayered optical thin films on the cleaved and polished flat end of a singlemode optical fiber. Recent work has studied the synthesis process and the fundamental mechanisms responsible for the change in optical reflection from such a multicomponent film that occurs as a function of humidity and various chemicals. We briefly review that prior work as a way to introduce more recent developments. The paper then discusses the application of these humidity sensors to the analysis of air flow associated with breathing [1]. We have designed the sensor thin film materials to enable the detection of relative humidity over a wide range, from approximately 5 to 95%, and for response times as short as several microseconds. This fast response time allows the near real-time analysis of air flow and water vapor transport during a single breath, with the advantage of very small size. The use of multiple sensors spaced a known distance apart allows the measurement of flow velocity, and recent work indicates a variation in sensor response versus coating thickness.

Commercial applications of metal rubber

This paper describes the commercial applications of Metal Rubber, the first material of its kind, a self-assembled free-standing electrically conductive elastomer in biomedical, aerospace and microelectronic areas. Metal Rubber is a novel nanocomposite formed via the self-assembly processing of metal nanoparticles and elastomeric polyectrolytes. This type of processing allows for control over bulk mechanical and electrical properties and requires only ppm quantities of metal to achieve percolation. The use of nanostructured precursors also results in transparent, electrically conductive nanocomposites. Metal Rubber elastomers are being developed as electrodes, for biomedical applications; flexible interconnects for microelectronics, and sensors to detect fatigue, impact and large strain for aerospace applications. This novel material may be formed as a conformal coating on nearly any substrate or as free standing films.

Metal Rubber electrodes for active polymer devices

This paper describes the use of Metal Rubber, which is an electrically conductive, low modulus, and optically transparent free-standing nanocomposite, as an electrode for active polymer devices. With its controllable and tailorable properties [such as modulus (from ~ 1 MPa to 100 MPa), electrical conductivity, sensitivity to flex and strain, thickness, transmission, glass transition, and more], Metal Rubber exhibits massive improvements over traditional stiff electrodes that physically constrain the actuator device motion and thus limit productivity. Metal Rubber shows exceptional potential for use as flexible electrodes for many active polymer applications.

Corrosion protection of surfaces by nanocomposite and urethane top coatings

In the present study, nanosized silica particles (~100 nm) were incorporated into epoxy polymers, and then sprayed on molybdenum treated Al coupons (2024-T3) by a nozzle spray unit at different thicknesses. A urethane top coating (1 mil) was also applied on some of the initially coated surfaces. The main purpose of the SiO2 and urethane was to absorb/block unwanted ions/molecules (i.e., Cl-, O, OH-, H2O, etc.) and increase the coating performance. Several corrosion tests including electrochemical impedance spectroscopy (EIS), salt spray and salt soaking were conducted on the prepared samples using a 0.5 M NaCl solution. The Al coupons coated with such nanocomposites and a urethane top coating showed excellent coating resistances (8x109 ohm-cm2) against corrosion attack. As a result, it is assumed that this novel coating system will allow coating industry to effectively protect the surface of materials.

Self-assembled nanostructured conducting elastomeric electrodes

We report the development of low modulus, highly conducting thin film electrodes formed by molecular-level self-assembly processing methods. The electrodes may be used on sensor or actuator materials requiring large strain.

Optical fiber sensors for breathing diagnostics

We report the application of an optical fiber-based humidity sensor to the problem of breathing diagnostics. The sensor is fabricated by molecularly self-assembling selected polymers and functionalized inorganic nanoclusters into multilayered optical thin films on the cleaved and polished flat end of a singlemode optical fiber. Prior work has studied the synthesis process and the fundamental mechanisms responsible for the change in optical reflection from such a multicomponent film that occurs as a function of humidity. We briefly review that prior work as a way to introduce more recent developments. We then discuss the application of these humidity sensors to the analysis of air flow associated with breathing. We have designed the sensor thin film materials to enable the detection of relative humidity over a wide range, from approximately 5 to 95%, and for response times as short as several microseconds. This fast response time allows the near real-time analysis of air flow and water vapor transport during a single breath, with the advantage of very small size. The use of multiple sensors spaced a known distance apart allows the measurement of flow velocity.

Metal Rubber sensors

We report recent improvements of Metal RubberTM strain sensors formed by electrostatic self-assembly (ESA) processing. The sensors may be used to measure strains from approximately 1 microstrain to several hundred percent strain, over gauge lengths ranging from approximately 1 millimeter to several tens of centimeters.

Nanostructured optical fiber sensors for breathing airflow monitoring

This paper presents recent progresses in the application of nanostructured optical fiber-based sensors for non-invasive, fast and reliable monitoring of respiratory airflow. Molecular-level self-assembly processing method is used to form multilayered inorganic nanocluster and polymer thin films on the distal ends of optical fibers to form such sensors. In order to optimize sensing performance, recent work has studies the synthesis process and the fundamental mechanisms for the change in optical reflection, specifically caused by exhaled air condensation on the coating surface. The physically small sensors fabricated by varying thin film chemistry, offer a full range of environmental relative humidity sensing from 0% to 100% with response times of microseconds, and mostly important, provide much higher sensitivity to breathing air, over 6 times larger than 100% relative humidity. The sensor performances in comparison with a medical nasal thermistor suggest such a thin film sensor an excellent device for advanced breathing airflow monitoring. All the features are appealing to clinical respiratory diagnosis and related sensor instrumentation design, and in good agreement with our analytical model.