Joseph Shinar - US grants

This composite project involves the collaboration of three departments in two separate universities. Novel conducting polymers that will be suitable for the optoelectronics industry will be studied, and will include the synthesis of new organosilicon polymers based on the incorporation of heteroelements into the carbon backbone structure of the polymers and their characterization by a variety of different techniques. Processing methods that will yield homogeneous thin films, coatings, and fibers of these polymers, that will be suitable for optical devices such as optical modulators and switches or electroluminescing (EL) devices will also be explored. Some of these new polymers will attract considerable scientific interest in the physics and chemistry communities by providing stable processible degenerate ground state polymers supporting charged solitons or EL systems, for which nongeminate decay processes will be studied in detail. This project is being supported jointly by the Division of Materials Research, and the Division of Electrical and Communications Systems.

Professor Joseph Shinar of Iowa State University is developing structurally integrated sensors utilizing an organic light emitting device for the detection of anthrax. The resulting battery-operated sensors will be ideal for applications in the area of homeland security as they are both selective and fast, but also inexpensive. The device takes the novel approach of integrating the excitation light source with the sensing component itself. This is expected to enhance detection sensitivity. While this new type of sensor is expected to have an immediate impact on homeland security it is also expected to lead to applications in medicine and environmental monitoring. A number of graduate students will participate in this highly interdisciplinary project and will be drawn from a variety of disciplines including physics, engineering, biophysics, molecular biology and chemistry.

This award is supported jointly by the NSF and the Intelligence Community. The Approaches to Combat Terrorism Program in the Directorate for Mathematics and Physical Sciences supports new concepts in basic research and workforce development with the potential to contribute to national security.

The objective of this research is to acquire research instrumentation for doing research on photonic waveguides and photonic devices, integrated biosensors, sensors for detection of toxic chemicals, organic semiconductors and neuron regrowth. These devices demand state of the art alignment capability with both front and back alignments. Iowa State has active research programs in each of the above areas, but does not have back and front sub-micron mask aligner. In this proposal, we plan to acquire a Suss MA/BA6 mask aligner capable of sub-micron lithography and of simultaneous back and front alignment so that device can be made on both sides of a substrate and devices in the submicron range can be made. This aligner will complement our existing array of tools, thereby allowing for a significant increase in our research productivity across a large number of disciplines.
Intellectual merit and Broad Impact
The proposed instrument meets a critical need at the University. No other comparable instrument is available at Iowa State. The instrument complements the following tools we own: Alcatel Deep RIE, poly-Si CVD furnace, Standard Si fabrication tools, Metal evaporators, Nanocrystalline Si plasma deposition reactors, Organic LED reactors, Single cantilever AFM tool. The instrument will allow faculty, students and research staff from Chemical Engineering, Electrical Engineering, Materials Science and Engineering, Mechanical Engineering, Physics, Chemistry and Biology to conduct experiments in the fields of photonic bandgaps, directed neural regrowth, nanocrystalline Si devices, integrated chemical and biological sensors based on OLED's and GMR devices, thin film resonators and multi-cantilver AFM tools for combinatorial diagnosis of surfaces. The instrument will be housed at the Microelectronics Research Center (MRC), an inter-disciplinary center at Iowa State where all the complementary facilities exist and are available for use by all the Iowa State faculty, staff and students. A full-time scientist will be in charge of the instrument and will maintain it in addition to some of the other tools. A maintenance account will be set up to charge the users a use-fee to pay for maintenance.
There will be significant impact on education of students, both graduate and undergraduate. This instrument, along with the existing instruments will be used for future experimental modules in courses dealing with fabrication of semiconductor, photonic and MEMS materials and devices Approximately 40 graduate students in many disciplines who use MRC facilities, and about 15 undergraduates who do research at MRC as part of their senior design or independent research projects will benefit from the acquisition of this instrument. A significant number of women and minority students are expected to participate in research activities made possible by the acquisition of this instrument. The proposed research activity has potentially broad impacts in the fields of electronic and photonic devices, sensors and neural science and engineering.

0428220
Shinar

The objective of this proposal is to develop novel photoluminescence
(PL)-based sensors that are fully structurally integrated: The light
source, the sensing element, and the photodetector (PD) and associated
filter, are fabricated on transparent substrates and attached
back-to-back. The resulting sensors could therefore be extremely
compact, robust, selective, fast, autonomous, consume little power, and
inexpensive. The proposal focuses on sensing oxygen, a key tool in
medical, environmental, (bio)chemical, and food monitoring, and Bacillus
anthracis toxin (anthrax).

The intellectual merit. The central concept is the novel total
structural integration of the foregoing components. The light source is
an array of organic light-emitting device (OLED) pixels. The sensing
elements include porous films with an embedded dye, surface immobilized
species whose PL is selectively analyte-sensitive, or microfluidic
channels/wells with recognition elements in solution. The PD and filter
are multilayer thin films of hydrogenated nanocrystalline Si, SiGe,
and/or SiC. The geometry will be "back detection," i.e., the OLED and PD
pixels are fabricated on the same side of the substrate. The array of
long-pass filters and PD pixels is fabricated first, followed by the
OLEDs in the gaps between the PD pixels. The sensing element is
fabricated on a separate substrate and attached to the OLED/PD
substrate. In the complete device, the electronic circuitry (including
instruction receiver and data transmitter), readout, and battery will be
positioned "behind" the PD. Hence the whole device would be ~2.5"x5"x1",
far more compact and less costly than any sensors currently available.
The work results in a new platform for PL-based sensors, which can be
further developed to multianalyte sensor microarrays. Innovative
elements are (i) the complete integration of all the sensor components,
and (ii) the development of sensing elements utilizing microfluidic
architectures and films/surfaces tailored for specific recognition
molecules, which will enhance the sensitivity and shorten the response
time. Moreover, the OLEDs will be operated in a pulsed mode, which will
increase their lifetime and generate negligible heat, which is crucial
for heat-sensitive recognition elements and agents. Oxygen will be
monitored via the PL lifetime, thus eliminating the need for frequent
calibration.

Different approaches will be evaluated to generate robust sensors for
real-world applications. The oxygen sensor will be based on the
dynamical quenching of the PL of oxygen-sensitive dyes, initially with a
green OLED and Pt octaethyl porphyrin (PtOEP) dye. We will compare the
sensors with dyes embedded in solid films with dyes solutions. The
anthrax sensor will be based on the cleavage of certain peptides by
anthrax lethal factor. Labeled peptides will be synthesized at the
Protein Facility of Iowa State University (ISU), with a Forster
resonance energy transfer donor and acceptor on either side of the
cleavage site.

The broader impacts. The sensors for the two aforementioned agents will
be ideal for a broad range of applications in areas such as homeland
security, medical, environmental, biological, food/brewing, and
health/safety. Beyond these impacts, the devices define a new sensor
platform for chemical and biological agents, which could lead to
extremely compact and inexpensive multianalyte sensor microarrays. The
proposed work will serve as a basis for the development of this
platform. It will also expand the basic knowledge in
embedding/immobilizing recognition elements, sensor design, and sensor
engineering. It will also have a broad educational impact, promoting the
growth of the interdisciplinary biophysics program at ISU and training
students in condensed matter physics, electrical engineering,
biophysics, chemistry, and molecular biology. It will be integrated with
teaching by developing new experimental course modules for graduate
students. Significant participation of undergraduates, including
minorities and women, is planned.

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).

The objective of this project is to acquire a nanolithography instrument, which will significantly improve the research capabilities at Iowa State and the University of Iowa in the fields of microelectronics, photonics and biology. The nanolithography instrument is an e-Line system, which is capable of 20 nm accuracy and can be used to make nano patterns over large areas.

Intellectual merit: The instrument allows for precise patterning at the nanoscale of electronic, photonic and biological materials and devices. It will allow fabrication of photonic crystal structures for improving the efficiency of solar cells. The instrument will be used for defining nanochannels for ordered regrowth of neurons and stem cells and for defining channels that will be utilized for studying the influence of various pesticides on mobility of nematodes, which are a major corn pest. The instrument will also be used to produce the patterns needed for negative index materials for advanced photonic devices such as waveguides and light valves.

Broad impacts: The technological impact of the research will be significant in many varied fields such as solar energy conversion, stem cell development, photonic devices and more efficient lighting. There will be significant integration of research and teaching through development of new lab courses and introduction of new lab modules in existing courses. Women and minority students at the graduate and undergraduate levels will be involved in the various research projects and will also benefit from the new lab classes that will be developed.

The objective of this program is to develop room-temperature electrophosphorescence (RT-EP) utilizing purely organic materials. These materials termed ?molecular alloys? are efficient phosphors as they transport charge, induce intersystem crossing from the singlet to triplet excited state, and lock the phosphors in a matrix preventing their nonradiative relaxation.
The materials displaying RT-EP will be investigated using optical spectroscopy and force microscopy (AFM, STM, C-AFM, KPM). Studies of polaron/exciton dynamics in films via photoluminescence (PL)- and photoinduced absorption (PA)-detected magnetic resonance (PLDMR and PADMR, respectively) will be carried out together with studies of polaron and exciton dynamics in the OLEDs using electroluminescence (EL)- and electrical current-detected
The intellectual merit: Electrophosphorescence from purely organic materials has so far been observed only at low temperature (~15 K), which prevents practical applications. The PVD materials termed ?molecular alloys? allow for efficient (EQE~3%) RT-EP in experimental devices. Thus, studies aimed at detailed understanding of the processes taking place in the all-organic phosphors-based devices are important.
The broader impacts are: Basic science proposed: An understanding of new all-organic materials that facilitate ISC while limiting nonradiative relaxation of the triplets and investigating physics of corresponding OLEDs will be achieved. Energy-conservation relevance: OLEDs as efficient light sources that would not require precious/heavy metals would be more environmentally friendly. Interdisciplinary Education: Collaboration between the two research groups with expertise in PVD, materials chemistry, condensed-matter physics, device fabrication and characterization will enrich education, encourage interdisciplinary thinking, and facilitate student exchange.

Malika Jeffries-EL of Iowa State University is funded by the Macromolecular, Supramolecular and Nanochemistry Program for collaborative research involving a team of scientists from both Iowa State and North Georgia College. The team is developing new electronics materials that are organic, meaning they are made from carbon-based molecules rather than the more commonly used inorganic materials, such as those based on silicon or germanium. In addition to their relative abundance, these organic materials have much lower fabrication costs and provide a range of properties not found in the inorganic substances. In this project, a combination of synthesis, theoretical calculations and physical measurement studies are being combined to design and fabricate working electronic devices. This work is having a broad impact not only on the electronics industry, but also by providing an interdisciplinary research experience for both undergraduate and graduate students, which fosters an interest in chemistry through a creative outreach effort targeting female and underrepresented minority students at all educational levels.

This project focuses on developing new cross-conjugated organic semiconductors for use in organic light emitting diodes and photovoltaic cells. In particular, novel cross-conjugated oligomers comprised of the robust benzobisoxazole (BBO) moiety are being studied. BBO is used as the electron-deficient building block since it is a unique cross-conjugated ring system that can be coupled either through the oxazole rings or through the central benzene ring, producing substances with different properties. The group is synthesizing materials with perpendicular conjugation axes because they have spatially segregated frontier molecular orbitals. This provides a means for semi-independent tuning of either the lowest unoccupied molecular orbital (LUMO) or highest occupied molecular orbital (HOMO). The benefits of the approach are that the cross-conjugated platform allows for the opportunity to optimize the material?s optical and electronic properties for specific applications. Various materials are being prepared and the most promising ones studied further by incorporation into working devices.

Abstract:
Non-Technical:
There is a growing need for small-size chemical and biological sensors to enable their integration into existing and developing technologies such as wearable electronics. The proposed research will address this need by developing such compact, sensitive, reliable, eventually user-friendly, inexpensive, flexible, and field-deployable sensors. In the long run the sensors will be adapted for applications such as medical testing, water and food quality monitoring, and security inspection. In addition to advancing the vital (bio) chemical sensing field, the project will benefit society by educating students in a diverse and highly interdisciplinary environment, producing highly qualified scientists/engineers who will contribute to this important multifaceted field, addressing key challenges in materials and device designs. The success of the project is expected to significantly advance the fields of thin film flexible electronics in conjunction with life-saving analytical applications.
Technical:
The specific goal of the proposed research is to advance the development of compact, sensitive, reliable, eventually user-friendly, inexpensive, flexible, and field-deployable, integrated photoluminescence (PL)-based chem/bio sensors, including in multiple analyte arrays. This objective addresses the growing need for continued miniaturization of sensors in applications such as medical testing, water and food quality monitoring, and security inspection. Moreover, such small-size sensors will enable their integration into existing and developing technologies, e.g., wearable electronics. To accomplish the objective of the proposed research fundamental science and engineering research is required. Thin film¡Vbased microcavity organic light emitting diodes (mcOLEDs) will be used as optical excitation sources; they will be integrated with hybrid, perovskite-based photodetectors (PDs). The mcOLEDs will be fabricated combinatorially on a single substrate, providing narrow emission bands (full width half max FWHM~20 nm). The emission peaks, produced by different active materials and microcavity dimensions, will range from the red to the near UV. The uniform dense array of such mcOLEDs, yet unachieved, will be integrated with two types of highly responsive perovskite PDs (an approach not yet explored): those responsive over a broad spectral range and those responsive over a narrow range. Bio/chem analytes will be monitored in two modes of operation, measuring analyte-induced changes in the (i) PL intensity using narrow-band PDs and (ii) PL decay time using both PD types. Developing both approaches will enhance selectivity and specificity. Importantly, to enable the advantageous PL monitoring where viable, the mcOLEDs and PDs will be evaluated and optimized to shorten the pulsed electroluminescence (EL) decay time and the PDs¡¦ response time by fundamental studies of their relation to materials, charge mobility, layer structures and thickness, defects, and device design. The integrated compact sensors will be demonstrated for two array types: (i) those operated by monitoring PL for, e.g., O2, dissolved O2, glucose, lactate, cholesterol, and ethanol, and (2) those operated largely by monitoring IPL as in e.g., pH measurement and immunoassays, which are of biological and health monitoring importance. The approaches outlined in this proposal will pave the way to miniaturized analytical tools on flexible substrates, integrated with microfluidic architectures. Array designs, attribute optimization, the demonstrated applications, and initial exploration of flexible devices are expected to significantly advance the fields of organic and hybrid electronics and analytical methodologies.