A. James Clark School of Engineering
Permanent URI for this communityhttp://hdl.handle.net/1903/1654
The collections in this community comprise faculty research works, as well as graduate theses and dissertations.
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Item Chitosan to Connect Biology to Electronics: Fabricating the Bio-Device Interface and Communicating Across This Interface(MDPI, 2014-12-24) Kim, Eunkyoung; Xiong, Yuan; Cheng, Yi; Wu, Hsuan-Chen; Liu, Yi; Morrow, Brian H.; Ben-Yoav, Hadar; Ghodssi, Reza; Rubloff, Gary W.; Shen, Jana; Bentley, William E.; Shi, Xiaowen; Payne, Gregory F.Individually, advances in microelectronics and biology transformed the way we live our lives. However, there remain few examples in which biology and electronics have been interfaced to create synergistic capabilities. We believe there are two major challenges to the integration of biological components into microelectronic systems: (i) assembly of the biological components at an electrode address, and (ii) communication between the assembled biological components and the underlying electrode. Chitosan possesses a unique combination of properties to meet these challenges and serve as an effective bio-device interface material. For assembly, chitosan’s pH-responsive film-forming properties allow it to “recognize” electrode-imposed signals and respond by self-assembling as a stable hydrogel film through a cathodic electrodeposition mechanism. A separate anodic electrodeposition mechanism was recently reported and this also allows chitosan hydrogel films to be assembled at an electrode address. Protein-based biofunctionality can be conferred to electrodeposited films through a variety of physical, chemical and biological methods. For communication, we are investigating redox-active catechol-modified chitosan films as an interface to bridge redox-based communication between biology and an electrode. Despite significant progress over the last decade, many questions still remain which warrants even deeper study of chitosan’s structure, properties, and functions.Item Catechol-Based Hydrogel for Chemical Information Processing(MDPI, 2017-07-03) Kim, Eunkyoung; Liu, Zhengchun; Liu, Yi; Bentley, William E.; Payne, Gregory F.Catechols offer diverse properties and are used in biology to perform various functions that range from adhesion (e.g., mussel proteins) to neurotransmission (e.g., dopamine), and mimicking the capabilities of biological catechols have yielded important new materials (e.g., polydopamine). It is well known that catechols are also redox-active and we have observed that biomimetic catechol-modified chitosan films are redox-active and possess interesting molecular electronic properties. In particular, these films can accept, store and donate electrons, and thus offer redox-capacitor capabilities. We are enlisting these capabilities to bridge communication between biology and electronics. Specifically, we are investigating an interactive redox-probing approach to access redox-based chemical information and convert this information into an electrical modality that facilitates analysis by methods from signal processing. In this review, we describe the broad vision and then cite recent examples in which the catechol–chitosan redox-capacitor can assist in accessing and understanding chemical information. Further, this redox-capacitor can be coupled with synthetic biology to enhance the power of chemical information processing. Potentially, the progress with this biomimetic catechol–chitosan film may even help in understanding how biology uses the redox properties of catechols for redox signaling.Item The Binding Effect of Proteins on Medications and Its Impact on Electrochemical Sensing: Antipsychotic Clozapine as a Case Study(MDPI, 2017-08-01) Banis, George E.; Winkler, Thomas; Barton, Patricia; Chocron, Sheryl E.; Kim, Eunkyoung; Kelly, Deanna L.; Payne, Gregory F.; Ben-Yoav, Hadar; Ghodssi, RezaClozapine (CLZ), a dibenzodiazepine, is demonstrated as the optimal antipsychotic for patients suffering from treatment-resistant schizophrenia. Like many other drugs, understanding the concentration of CLZ in a patient’s blood is critical for managing the patients’ symptoms, side effects, and overall treatment efficacy. To that end, various electrochemical techniques have been adapted due to their capabilities in concentration-dependent sensing. An open question associated with electrochemical CLZ monitoring is whether drug–protein complexes (i.e., CLZ bound to native blood proteins, such as serum albumin (SA) or alpha-1 acid-glycoprotein (AAG)) contribute to electrochemical redox signals. Here, we investigate CLZ-sensing performance using fundamental electrochemical methods with respect to the impact of protein binding. Specifically, we test the activity of bound and free fractions of a mixture of CLZ and either bovine SA or human AAG. Results suggest that bound complexes do not significantly contribute to the electrochemical signal for mixtures of CLZ with AAG or SA. Moreover, the fraction of CLZ bound to protein is relatively constant at 31% (AAG) and 73% (SA) in isolation with varying concentrations of CLZ. Thus, electrochemical sensing can enable direct monitoring of only the unbound CLZ, previously only accessible via equilibrium dialysis. The methods utilized in this work offer potential as a blueprint in developing electrochemical sensors for application to other redox-active medications with high protein binding more generally. This demonstrates that electrochemical sensing can be a new tool in accessing information not easily available previously, useful toward optimizing treatment regimens.Item DEVELOPMENT OF VAPOR-PHASE DEPOSITED THREE DIMENSIONAL ALL-SOLID-STATE BATTERIES(2017) Pearse, Alexander John; Rubloff, Gary; Material Science and Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Thin film solid state batteries (SSBs) are an attractive energy storage technology due to their intrinsic safety, stability, and tailorable form factor. However, as thin film SSBs are typically fabricated only on planar substrates by line-of-sight deposition techniques (e.g. RF sputtering or evaporation), their areal energy storage capacity (< 1 mWh/cm2) and application space is highly limited. Moving to three dimensional architectures provides fundamentally new opportunities in power/energy areal density scaling, but requires a new fabrication process. In this thesis, we describe the development of the first solid state battery chemistry which is grown entirely by atomic layer deposition (ALD), a conformal, vapor-phase deposition technique. We first show the importance of full self-alignment of the active battery layers by measuring and modelling the effects of nonuniform architectures (i.e. does not reduce to a one-dimensional system) on the internal reaction current distribution. By fabricating electrochemical test structures for which generated electrochemical gradients are parallel to the surface, we directly quantify the insertion of lithium into a model cathode material (V2O5) using spatially-resolved x-ray photoelectron spectroscopy (XPS). Using this new technique, we show that poorly electrically contacted high aspect ratio structures show highly nonuniform reaction current distributions, which we describe using an analytical mathematical model incorporating nonlinear Tafel kinetics. A finite-element model incorporating the effects of Li-doping on the local electrical conductivity of V2O5, which was found to be important in describing the observed distributions, is also described. Next, we describe the development of a novel solid state electrolyte, lithium polyphosphazene (LPZ), grown by ALD. We explore the thermal ALD reaction between lithium tert-butoxide and diethyl phosphoramidate, which exhibits self-limiting half-reactions and a growth rate of 0.09 nm/cycle at 300C. The resulting films are primarily characterized by in-situ XPS, AFM, cyclic voltammetry, and impedance spectroscopy. The ALD reaction forms the amorphous product Li2PO2N along with residual hydrocarbon contamination, which is determined to be a promising solid electrolyte with an ionic conductivity of 6.5 × 10-7 S/cm at 35C and wide electrochemical stability window of 0-5.3 V vs. Li/Li+ . The ALD LPZ is integrated into a variety of solid state batteries to test its compatibility with common electrode materials, including LiCoO2 and LiV2O5, as well as flexible substrates. We demonstrate solid state batteries with extraordinarily thin solid state electrolytes, mitigating the moderate ionic conductivity (< 40 nm). Finally, we describe the successful integration of the ALD LPZ into the first all-ALD solid state battery stack, which is conformally deposited onto 3D micromachined silicon substrates and is fabricated entirely at or below 250C. The battery includes ALD current collectors (Ru and TiN), an electrochemically formed LiV2O5 cathode, and a novel ALD tin nitride conversion-type anode. The full cell exhibits a reversible capacity of ~35 μAh cm-2 μmLVO -1 with an average discharge voltage of ~2V. We also describe a novel fabrication process for forming all-ALD battery cells, which is challenging due to ALD’s incompatibility with conventional lithography. By growing the batteries into 3D arrays of varying aspect ratios, we demonstrate upscaling the areal capacity of the battery by approximately one order of magnitude while simultaneously improving the rate performance and round-trip efficiency.Item The Binding Effect of Proteins on Medications and Its Impact on Electrochemical Sensing: Antipsychotic Clozapine as a Case Study(Multidisciplinary Digital Publishing Institute (MDPI), 2017-08-01) Banis, George E.; Winkler, Thomas; Barton, Patricia; Chocron, Sheryl E.; Kim, Eunkyoung; Kelly, Deanna L.; Payne, Gregory F.; Ben-Yoav, Hadar; Ghodssi, RezaClozapine (CLZ), a dibenzodiazepine, is demonstrated as the optimal antipsychotic for patients suffering from treatment-resistant schizophrenia. Like many other drugs, understanding the concentration of CLZ in a patient’s blood is critical for managing the patients’ symptoms, side effects, and overall treatment efficacy. To that end, various electrochemical techniques have been adapted due to their capabilities in concentration-dependent sensing. An open question associated with electrochemical CLZ monitoring is whether drug–protein complexes (i.e., CLZ bound to native blood proteins, such as serum albumin (SA) or alpha-1 acid-glycoprotein (AAG)) contribute to electrochemical redox signals. Here, we investigate CLZ-sensing performance using fundamental electrochemical methods with respect to the impact of protein binding. Specifically, we test the activity of bound and free fractions of a mixture of CLZ and either bovine SA or human AAG. Results suggest that bound complexes do not significantly contribute to the electrochemical signal for mixtures of CLZ with AAG or SA. Moreover, the fraction of CLZ bound to protein is relatively constant at 31% (AAG) and 73% (SA) in isolation with varying concentrations of CLZ. Thus, electrochemical sensing can enable direct monitoring of only the unbound CLZ, previously only accessible via equilibrium dialysis. The methods utilized in this work offer potential as a blueprint in developing electrochemical sensors for application to other redox-active medications with high protein binding more generally. This demonstrates that electrochemical sensing can be a new tool in accessing information not easily available previously, useful toward optimizing treatment regimens.Item Beyond Li ion: Rechargeable Metal Batteries based on Multivalent Chemistry(2017) Gao, Tao; Wang, Chunsheng; Chemical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The development of advanced battery technology with lower cost and higher energy density is important since various mobile applications are becoming indispensable in our daily life. While Li chemistry has approached its theoretical limit after several decades’ increment improvement, the potential of multivalent chemistry (Mg, Al, etc.) remains unexplored. Compared to Li ion chemistry, multivalent chemistry provides many intriguing benefits in terms of lowering cost and increasing energy density. First of all, minerals containing multivalent element such as Mg, Al, and etc. are much more abundant and cheaper than Li. Second, multivalent metals (Mg, Al etc.) can be directly used as anode materials, ensuring much higher anode capacity than graphite currently used in Li-ion battery. Third, the divalent or trivalent nature of the electroactive cation (Mg2+and Al3+) also promise high capacity for intercalation cathodes because the capacity of these materials are limited by their available ion occupancy sites in the crystal structure instead of its capability to accept electrons. In this dissertation, I detailed our efforts in examining some redox chemistries and materials for the use of rechargeable batteries based on multivalent metal anodes. They include intercalation cathode (TiS2) and conversion cathode (sulfur, iodine). We studied their electrochemical redox behavior in the corresponding chemistry, the thermodynamics, kinetics as well as the reaction reversibility. The reaction mechanism is also investigated with various macroscopic and spectroscopic techniques.Item Microsystems Integration Towards Point-of-Care Monitoring of Clozapine Treatment for Adherence, Efficacy, and Safety(2017) Winkler, Thomas E.; Ghodssi, Reza; Bioengineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Schizophrenia is a challenging and complex disorder with 30–50% of patients not responding to first line antipsychotic treatment. Clozapine is the only antipsychotic approved by the FDA for treatment-resistant schizophrenia and is the most effective antipsychotic medication currently available. Yet, clozapine remains underutilized because of the requirements for frequent invasive and burdensome monitoring to 1) titrate doses to achieve effective blood levels, as well as 2) monitor white blood cells on a weekly basis for the first six months due to risk of agranulocytosis, a rare but potentially fatal side effect of clozapine. These blood draws, and the time lag in receiving reports from central labs, can add several more visits to the caregivers' treatment plan, which may not be feasible for the patient nor the treatment team. This contributes to a very low prescription rate for clozapine, making it one of the most underutilized evidence-based treatments in the field of mental health. The objective of this work is to progress toward a point-of-care approach to monitor both white blood cells and clozapine within a clinical setting. This would significantly lower the burden associated with clozapine treatment by allowing both tests to be performed rapidly during a single doctor's office visit or at the pharmacy. Specifically, I have developed and studied novel clozapine detection schemes based on electrochemical signal amplification in chitosan-based films. Moreover, I have investigated impedance cytometry coupled with hydrodynamic focusing and osmotic lysis to provide label- and reagent-free differential white blood cell counting capabilities. Finally, I have integrated the components in a microsystem capable of concurrent sensing of both biomarkers in whole blood samples. This proof-of-concept device lays the foundation for a fully integrated and automated lab-on-a-chip for point-of-care or even at-home testing to ensure treatment adherence, efficacy, and safety. This will allow for broader use of clozapine by increasing convenience to patients as well as medical professionals, thus improving the lives of people affected by schizophrenia through personalized medicine.Item Bridging the biology-electronics communication gap with redox signaling(2015) Gordonov, Tanya; Bentley, William E; Bioengineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Electronic and biological systems both have the ability to sense, respond to, and communicate relevant data. This dissertation aims to facilitate communication between the two and create bio-hybrid devices that can process the breadths of both electronic and biological information. We describe the development of novel methods that bridge this bi-directional communication gap through the use of electronically and biologically relevant redox molecules for controlled and quantitative information transfer. Additionally, we demonstrate that the incorporation of biological components onto microelectronic systems can open doors for improved capabilities in a variety of fields. First, we describe the original use of redox molecules to electronically control the activity of an enzyme on a chip. Using biofabrication techniques, we assembled HLPT, a fusion protein which generates the quorum sensing molecule autoinducer-2, on an electrodeposited chitosan film on top of an electrode. This allows the electrode to controllably oxidize the enzyme in situ through a redox mediator, acetosyringone. We successfully showed that activity decrease and bacterial quorum sensing response are proportional to the input charge. To engineer bio-electronic communication with cells, we first aimed for better characterizing an electronic method for measuring cell response. We engineered Escherichia coli (E.coli) cells to respond to autoinducer-2 by producing the β-galactosidase enzyme. We then investigated an existing electrochemical method for detecting β-galactosidase activity by measuring a redox-active product of the cleavage of the added substrate molecule PAPG. In our novel findings, the product, PAP, was found to be produced at a rate that correlated with the standard spectrophotometric method for measuring β-galactosidase, the Miller assay, in both whole live and lysed cells. Conversely, to translate electronic signals to something cells can understand, we used pyocyanin, a redox drug which oxidizes the E.coli SoxR protein and allows transcription from the soxS promoter. We utilized electronic control of ferricyanide, an electron acceptor, to amplify the production of a reporter from soxS. With this novel method, we show that production of reporter depends on the frequency and amplitude of electronic signals, and investigate the method’s metabolic effects. Overall, the work in this dissertation makes strides towards the greater goal of creating multi-functional bio-hybrid devices.