Ronald James Wroczynski

Theory and practice of ubiquitous quantitative chemical analysis using conventional computer optical disk drives.

We demonstrate a new attractive approach for ubiquitous quantitative chemical or biological sensing when analog signals are acquired from conventional optical disk drives, and these signals are used for quantitative detection of optical changes of sensing films deposited on conventional CD and DVD optical disks. Our developed analytical model of the operation of this Lab-on-DVD system describes the optical response of sensing films deposited onto the read surface of optical disks by taking into account the practical aspects of system performance that include possible reagent leaching effects, water sampling (delivering) efficiency, and possible changes of the film morphology after water removal. By applying a screen-printing process, we demonstrated a laboratory-scale automated production of sensing films with an average thickness of approximately 10 microm and a thickness relative standard deviation of <3% across multiple films. Finally, we developed a system for delivery of water-sample volumes to sensing films on the disk that utilized a multifunctional jewel case assembly.

Multifunctional sensor system for high-throughput primary, secondary, and tertiary screening of combinatorial materials

A modular multifunctional acoustic wave thickness shear mode sensor system has been designed and implemented for the rapid characterization of materials. The sensors are arranged as a 6×4 array and are compatible with available 24-well plates for manipulation with standard robotic equipment. The sensor system has two types of sensor enclosures including a gas-flowthough cell for studies of vapor-sorption properties and weathering of materials and a platform for immersion of sensors into 24-well plate arrays for studies of materials solubility. In addition, the sensor array design can be operated remotely from the rest of electronic components to decouple the environment of sensor array exposure (e.g., high temperature, pressure, chemicals). This sensor system has been used to screen sensor materials to emphasize (1) the magnitude of sensor response to the parameter of interest; (2) sensor specificity against environmental interferences; and (3) long-term stability. This work for the first time addresses a...

Spectroscopic and imaging approaches for evaluation of properties of one-dimensional arrays of formulated polymeric materials fabricated in a combinatorial microextruder system

We report optical spectroscopic and imaging approaches for the high-throughput nondestructive characterization of formulated polymeric materials fabricated as one-dimensional (1D) polymeric arrays. These materials are fabricated as 1–2 mm diameter fibers or 5–12-mm-wide by 0.3–1-mm-thick films using a combinatorial system that includes a microextruder (total barrel volume of 4.5cm3) and microfeeders. Because our microextruder approach for fabrication of formulated polymeric materials requires ∼200 times less material compared to traditional scale extruders, it provides previously unavailable opportunities for characterization of extruded materials without their pelletization. Property changes in polymeric formulations are induced along the length of the 1D arrays by several approaches that include (1) variation in composition of 1D array during polymer microextrusion, (2) variation in processing conditions during polymer microextrusion, and (3) variation in exposure conditions of a performance test for di...

Improved Specific Biodetection with Ion Trap Mobility Spectrometry (ITMS): A 10-min, Multiplexed, Immunomagnetic ELISA

Enabling trace chemical detection equipment utilized in the field to transduce a biodetection assay would be advantageous from a logistics, training, and maintenance standpoint. Described herein is an assay design that uses an unmodified, commercial off-the-shelf (COTS) ion trap mobility spectrometer to analyze an immunomagnetic enzyme-linked immunosorbant assay (ELISA). The assay, which uses undetectable enzymatic substrates and ELISA-generated detectable products, was optimized to quantitatively report the amount of target in the sample. Optimization of this ELISA design retained the assay specificity and detection limit (approximately 10(3) E. coli per assay) while decreasing the number of user steps and reducing the assay time to 10 min (>9-fold decrease as compared to past studies). Also discussed are previously undescribed, independent substrate/enzyme/product combinations used in the immunomagnetic ELISA. These discoveries allow for the possibility of a quantitative, multiplexed, 10-min assay that is analyzed by the ion trap mobility spectrometer trace chemical detector.

Determination of oxidative stability of polypropylene using chemical sensors

Rapid determination of thermal oxidative stability of polymers during processing is required for the high-throughput evaluation of efficiency of anti-oxidant additive formulations. A conventional method for determination of thermal oxidative stability of polypropylene involves the analysis of melt flow index (MFI) after multiple extrusions. While these measurements are reliable and well accepted, they are also time consuming, require a relatively large amount of material for analysis, and are destructive. Realizing these prominent limitations of MFI analysis, measurements of volatiles were performed using an array of metal oxide semiconductor chemical sensors. This approach can provide descriptive information about the polypropylene oxidative stability after multiple-pass extrusions and can be applicable for the high-throughput ranking of oxidative stability of polypropylene formulations.

Acoustic Wave Sensors for High-Throughput Screening of Materials

Sensors are well-accepted analytical instruments for the measurement of a diverse range of chemical and physical parameters [1, 2, 3, 4, 5, 6]. For combinatorial and high-throughput (HT) screening, sensors are almost an ideal screening tool for a variety of material applications. Indeed, sensors are already miniaturized and do detect quantitatively small amounts of materials. Also, sensors are often multiplexed into arrays for improvement of selectivity and overall performance. In addition, data analysis from sensor arrays is well understood. Finally, different types of sensor transduction mechanisms are known and available to fit particular HT applications. Thus it is relatively straightforward to adapt advances in sensor development for combinatorial screening applications. Table 11.1 compares the capabilities of an ideal high-throughput screening (HTS) tool with the reported capabilities of sensors for a variety of combinatorial and other applications and demonstrates the growing potential of sensors for combinatorial screening.

Determination of Quantitative Structure–Property Relationships of Solvent Resistance of Polycarbonate Copolymers Using a Resonant Multisensor System

In sensor and microfluidic applications, the need is to have an adequate solvent resistance of polymers to prevent degradation of the substrate surface upon deposition of sensor formilations, to prevent contamination of the solvent-containing sensor formulations or contamination of organic liquid reactions in microfluidic channels. Unfortunately, no comprehensive quantitative reference solubility data of unstressed copolymers is available to date. In this study, we evaluate solvent-resistance of several polycarbonate copolymers prepared from the reaction of hydroquinone (HQ), resorcinol (RS), and bisphenol A (BPA). Our high-throughput polymer evaluation approach permitted the construction of detailed solvent-resistance maps, the development of quantitative structure–property relationships for BPA-HQ-RS copolymers and provided new knowledge for the further development of the polymeric sensor and microfluidic components.

Applications of Discrete and Gradient Compositions in Polymer Research

A new general approach for rapid performance screening of polymer compositions is provided. Multiple compositions are generated as one-dimensional libraries in a micro-extruder with step or gradient composition changes in