Without her selfless love, guidance and prayers, not only would the achievement of this degree be... more Without her selfless love, guidance and prayers, not only would the achievement of this degree be impossible, but similarly, all previous and subsequent personal accomplishments. My hope and goal for myself is that I am able to adequately honor her memory from this point forward in all of my choices, acts and deeds. I would like to thank my advisors, Drs. Wei-Heng and Wan Y. Shih for five years of guidance, advice and discussion. I cannot quantify the knowledge and experience I have gained. I'd also like to thank my examination committee members for their time and input, as well as members of the Ceramics Sensors and Processing Group; specifically,
The component part is provided here to allow users access to individually authored sections f pro... more The component part is provided here to allow users access to individually authored sections f proceedings, annals, symposia, etc. However, the component should be considered within [he context of the overall compilation report and not as a stand-alone technical report. The following component part numbers comprise the compilation report: ADP019693 thru ADP019749
The development of a serum protein detector will provide opportunities for better screening of at... more The development of a serum protein detector will provide opportunities for better screening of at‐risk cancer patients, tighter surveillance of disease recurrence and better monitoring of treatment. An integrated system that can process clinical samples for a number of different types of biomarkers would be a useful tool in the early detection of cancer. Also, screening iomarkers such as antibodies in serum would provide clinicians with information regarding the patient's response to treatment. Therefore, the goal of this study is to develop a sensor which can be used for rapid, all‐electrical, real‐time, label‐fee, in‐situ, specific quantification of cancer markers, e.g., human epidermal receptor 2 (Her2)or antibodies, in serum. To achieve this end, piezoelectric microcantilever sensors (PEMS) were constructed using an 8 μm thick lead magnesium niobate‐lead titanate (PMN‐PT) freestanding film as the piezoelectric layer. The desired limit of detection is on the order of pg/mL. In order to achieve this goal the higher frequency lateral extension modes were used. Also, as the driving and sensing of the PEMS is electrical, the PEMS must be insulated in a manner that allows it to function in aqueous solutions. The insulation layer must also be compatible with standardized bioconjugation techniques. Finally, detection of both cancer antigens and antibodies in serum was carried out, and the results were compared to a standard commercialized protocol. PEMS have demonstrated the capability of detecting Her2 at a concentration of 5 pg/mL in diluted human serum (1:40) in less than 1 hour. The approach can be easily translated into the clinical setting because the sensitivity is more than sufficient for monitoring prognosis of breast cancer patients. In addition to Her2 detection, antibodies in serum were assayed in order to demonstrate the feasibility of monitoring the immune response for antibody‐dependent cellular cytotoxicity (ADCC) in patients on antibody therapies such as Herceptin and Cetuximab. The PEMS displayed a [...]
Quantum Dots (QDs) are semiconductor nanocrystals (1~20 nm) exhibiting distinctive photoluminesce... more Quantum Dots (QDs) are semiconductor nanocrystals (1~20 nm) exhibiting distinctive photoluminescence (PL) properties due to the quantum confinement effect. Having many advantages over organic dyes, such as broad excitation and resistance to photobleaching, QDs are widely used in bioapplications as one of most exciting nanobiotechnologies.To date, most commercial QDs are synthesized through the traditional organometallic method and contain toxic elements, such as cadmium, lead, mercury, arsenic, etc. The overall goal of this thesis study is to develop an aqueous synthesis method to produce nontoxic quantum dots with strong emission and good stability, suitable for biomedical imaging applications.Firstly, an aqueous, simple, environmentally friendly synthesis method was developed. With cadmium sulfide (CdS) QDs as an example system, various processing parameters and capping molecules were examined to improve the synthesis and optimize the PL properties. The obtained water soluble QDs exhibited ultra small size (~5 nm), strong PL and good stability. Thereafter, using the aqueous method, the zinc sulfide (ZnS) QDs were synthesized with different capping molecules, i.e., 3-mercaptopropionic acid (MPA) and 3-(mercaptopropyl)trimethoxysilane (MPS). Especially, via a newly developed capping molecule replacement method, the present ZnS QDs exhibited bright blue emission with a quantum yield of 75% and more than 60 days lifetime in the ambient conditions. Two cytotoxicity tests with human endothelial cells verified the nontoxicity of the ZnS QDs by cell counting with Trypan blue staining and fluorescence assay with Alamar Blue. Taking advantage of the versatile surface chemistry, several strategies were explored to conjugate the water soluble QDs with biomolecules, i.e., antibody and streptavidin. Accordingly, the imaging of Salmonella t. cells and biotinylated microbeads has been successfully demonstrated. In addition, polyethylenimine (PEI)-QDs complex was formed and delivered into PC12 neuronal cells for intracellular i [...]
Cesium lead halide perovskite nanocrystals have a narrow emission peak tunable in the visible wav... more Cesium lead halide perovskite nanocrystals have a narrow emission peak tunable in the visible wavelength range with a high quantum yield. They hold great potential for optoelectronic applications such as light-emitting diodes or electronic displays. However, cesium lead iodide (CsPbI 3) is not stable under ambient conditions, limiting its applications. Here, we use a solution surface treatment approach to improve the photostability of CsPbI 3 suspensions in toluene. When a CsPbBr 3 precursor is used via the method of heterogeneous surface treatment, the photoluminescence (PL) intensity is enhanced but the PL only lasts 2 days. In contrast, when a CsPbI 3 precursor is used via the method of homogeneous surface treatment, not only the PL intensity of CsPbI 3 suspensions is enhanced but also the stability with the PL lasts for 11 days. It is likely that a better protection on the core CsPbI 3 by itself can be achieved because of better matching of the material structure and surface chemistry.
• Tin sulfide (SnS) quantum dots were surface treated with Zinc Sulfide (ZnS) precursors. • Surfa... more • Tin sulfide (SnS) quantum dots were surface treated with Zinc Sulfide (ZnS) precursors. • Surface treatment increased SnS QD photoluminescence by 20x without affecting emission wavelength. • Improved stability of SnS/ZnS QD suspensions in glycerol in a wide pH range with mercaptopropionic acid (MPA) • Improved stability of SnS/ZnS QD in aqueous suspensions using mercaptopropylsilane (MPS)
Current genetic detection methods require gene isolation, gene amplification and detection with a... more Current genetic detection methods require gene isolation, gene amplification and detection with a fluorescent-tagged probe. They typically require sophisticated equipment and expensive fluorescent probes, rendering them not widely available for rapid acute infection diagnoses at the point of care to ensure timely treatment of the diseases. Here we report a rapid genetic detection method that can detect the bacterial gene directly from patient stools using a piezoelectric plate sensor (PEPS) in conjunction with a continuous flow system with two temperature zones. With stools spiked with sodium dodecyl sulfate (SDS) in situ bacteria lysing and DNA denaturation occurred in the high-temperature zone whereas in situ specific detection of the denatured DNA by the PEPS occurred in the lower-temperature zone. The outcome was a rapid genetic detection 2 method that directly detected bacterial genes from stool in <40 min without the need of gene isolation, gene amplification, or expensive fluorescent tag but with polymerase chain reaction (PCR) sensitivity. In 40 blinded patient stools, it detected the toxin B gene of Clostridium difficile with 95% sensitivity and 95% specificity. The all-electrical, label-free nature of the detection further supports its potential as a low-cost genetic test that can be used at the point of care.
We have investigated amplification-free in situ double-stranded mutation detection in urine in th... more We have investigated amplification-free in situ double-stranded mutation detection in urine in the concentration range 10 M - 10 M using piezoelectric plate sensors (PEPs). The detection was carried out in a close-loop flow with two temperature zones. The 95 °C high-temperature zone served as the reservoir where the sample was loaded and DNA de-hybridized. The heated urine was cooled flowing through a 1 m long tubing immersed in room-temperature water bath at a flow rate of 4 ml/min to reach the detection cell at the desired temperature for the detection to take place. With hepatitis B virus double mutation (HBVDM) and KRAS G12V point mutation as model double mutations, it is shown that PEPS was able to detect double-stranded HBVDM and KRAS with 70% detection efficiency or better at concentration as low as 10 M against single-stranded mutation detection at the same concentrations, which was validated by the following in situ fluorescent reporter microspheres (FRMs) detection as wel...
Nanodesigning of multifunctional ceramic composites with colloids is discussed from a fundamental... more Nanodesigning of multifunctional ceramic composites with colloids is discussed from a fundamental point of view. We start with one-component systems, where packing density is the primary concern. Then we extend the discussion to binary systems and deal with the problem of homogeneity. We show that the structure is controlled by the nature of bonding between the particles and by the particle-particle interaction. Surfactants are used to modiy these properties, by, first, protecting the active particle surfaces to prevent solid bond formation, and, second, altering the interparticle interaction to provide a “lubricating” effect. In weakly attractive multicomponent systems, not only are we able to achieve high-density packing through restructuring, but we can also control the scale of homogeneity.
ABSTRACT We examined the effect of the boehmite coating thickness on the rheology and consolidati... more ABSTRACT We examined the effect of the boehmite coating thickness on the rheology and consolidation of boehmite-coated SiC suspensions. The thickness of the boehmite coating on SiC was varied by adjusting the boehmite concentration relative to SiC. For boehmite concentrations less than 10 wt%, the coating thickness increased with increasing boehmite concentration. For boehmite concentrations higher than 10 wt%, the coating thickness saturated. Further increase in the boehmite concentration led to the presence of small boehmite particles in the suspensions. All boehmite-coated suspensions gelled near their isoelectric points and the storage moduli of the gels with respect to pH exhibited a maximum near the isoelectric points. Below 10 wt% boehmite, the suspensions had very few small boehmite particles. The maximum storage modulus, G′0,max, of the boehmite-coated SiC gel decreased with increasing coating thickness, t, as G′0,max∝t−2, in good agreement with our earlier theoretical prediction. Meanwhile, the maximum sedimentation densities, φmax, of the coated suspensions occurred at around pH ∼ 4.0 and increased with increasing coating thickness from under φmax= 25 vol% with 1 wt% boehmite to above φmax= 65 vol% with 10 wt% boehmite due to increased zeta potential with increasing coating thickness. Above 10 wt% boehmite, the excess boehmite particles in the suspension increased the maximum suspension storage modulus, G′0,max, and decreased the maximum sedimentation density, φmax.
Aggregation of colloidal particles with a finite attraction energy was investigated with computer... more Aggregation of colloidal particles with a finite attraction energy was investigated with computer simulations and with gold particles coated with a surfactant. Computer simulations were carried out with the Shih-Aksay-Kikuchi (SAK) model, which incorporates a finite nearest-neighbor attraction energy-E into the diffusion-limited-cluster-aggregation (DLCA) model. Both the computer simulations and the experiments showed that (i) with a finite interparticle attraction energy, aggregates can still remain fractal, and (ii) the fractal dimension remains unchanged at large interparticle attraction energies and increases when the interparticle attraction energy is smaller than 4k~ T, where Tis the tcmperalurc and k. is the B~)ltzmann constant. The agrcemcnl between the simulations and the experimental results suggests that the reversiblc aggregation process in a colloidal system can be represented by the SAK model.
For piezoelectric microcantilever sensors (PEMSs) whose resonance frequency shift during detectio... more For piezoelectric microcantilever sensors (PEMSs) whose resonance frequency shift during detection is due to Young’s modulus change in the piezoelectric layer, we showed that their detection longitudinal flexural resonance frequency shift, Δf, is inversely proportional to the square of the PEMS length, L2; their relative resonance frequency shift, Δf/f, inversely proportional to the PEMS thickness, t; and their mass detection sensitivity, Δf/Δm, inversely proportional to wL3 where w is the width. The resonance frequency shift caused by Young’s modulus change in the piezoelectric layer is more than 300 times larger than would be expected from the mass change.
In this study, we examined how the materials’ properties of a lead magnesium niobate-lead titanat... more In this study, we examined how the materials’ properties of a lead magnesium niobate-lead titanate solid solution, [Pb(Mg1/3Nb2/3)O3]0.63[PbTiO3]0.37 (PMN-PT) piezoelectric plate sensor (PEPS) affected the enhancement of the relative detection resonance frequency shift, −Δf/f of the sensor, where f and Δf were the resonance frequency and resonance frequency shift of the sensor, respectively. Specifically, the electromechanical coupling constant, −k31, of the PMN-PT PEPS was varied by changing the grain size of the piezoelectric layer as well as by applying a bias direct current electric field. Detection of streptavidin at the same concentration was carried out with biotin covalently immobilized on the surface of PEPS. It is shown that the −Δf/f of the same streptavidin detection was increased by more than 2-fold when the −k31 increased from 0.285 to 0.391.
We have examined the in situ detection of a single-nucleotide KRAS mutation in urine using a (Pb(... more We have examined the in situ detection of a single-nucleotide KRAS mutation in urine using a (Pb(Mg1/3Nb2/3)O3)0.65(PbTiO3)0.35 (PMN-PT) piezoelectric plate sensor (PEPS) coated with a 17-nucleotide (nt) locked nucleic acid (LNA) probe DNA complementary to the KRAS mutation.
Without her selfless love, guidance and prayers, not only would the achievement of this degree be... more Without her selfless love, guidance and prayers, not only would the achievement of this degree be impossible, but similarly, all previous and subsequent personal accomplishments. My hope and goal for myself is that I am able to adequately honor her memory from this point forward in all of my choices, acts and deeds. I would like to thank my advisors, Drs. Wei-Heng and Wan Y. Shih for five years of guidance, advice and discussion. I cannot quantify the knowledge and experience I have gained. I'd also like to thank my examination committee members for their time and input, as well as members of the Ceramics Sensors and Processing Group; specifically,
The component part is provided here to allow users access to individually authored sections f pro... more The component part is provided here to allow users access to individually authored sections f proceedings, annals, symposia, etc. However, the component should be considered within [he context of the overall compilation report and not as a stand-alone technical report. The following component part numbers comprise the compilation report: ADP019693 thru ADP019749
The development of a serum protein detector will provide opportunities for better screening of at... more The development of a serum protein detector will provide opportunities for better screening of at‐risk cancer patients, tighter surveillance of disease recurrence and better monitoring of treatment. An integrated system that can process clinical samples for a number of different types of biomarkers would be a useful tool in the early detection of cancer. Also, screening iomarkers such as antibodies in serum would provide clinicians with information regarding the patient's response to treatment. Therefore, the goal of this study is to develop a sensor which can be used for rapid, all‐electrical, real‐time, label‐fee, in‐situ, specific quantification of cancer markers, e.g., human epidermal receptor 2 (Her2)or antibodies, in serum. To achieve this end, piezoelectric microcantilever sensors (PEMS) were constructed using an 8 μm thick lead magnesium niobate‐lead titanate (PMN‐PT) freestanding film as the piezoelectric layer. The desired limit of detection is on the order of pg/mL. In order to achieve this goal the higher frequency lateral extension modes were used. Also, as the driving and sensing of the PEMS is electrical, the PEMS must be insulated in a manner that allows it to function in aqueous solutions. The insulation layer must also be compatible with standardized bioconjugation techniques. Finally, detection of both cancer antigens and antibodies in serum was carried out, and the results were compared to a standard commercialized protocol. PEMS have demonstrated the capability of detecting Her2 at a concentration of 5 pg/mL in diluted human serum (1:40) in less than 1 hour. The approach can be easily translated into the clinical setting because the sensitivity is more than sufficient for monitoring prognosis of breast cancer patients. In addition to Her2 detection, antibodies in serum were assayed in order to demonstrate the feasibility of monitoring the immune response for antibody‐dependent cellular cytotoxicity (ADCC) in patients on antibody therapies such as Herceptin and Cetuximab. The PEMS displayed a [...]
Quantum Dots (QDs) are semiconductor nanocrystals (1~20 nm) exhibiting distinctive photoluminesce... more Quantum Dots (QDs) are semiconductor nanocrystals (1~20 nm) exhibiting distinctive photoluminescence (PL) properties due to the quantum confinement effect. Having many advantages over organic dyes, such as broad excitation and resistance to photobleaching, QDs are widely used in bioapplications as one of most exciting nanobiotechnologies.To date, most commercial QDs are synthesized through the traditional organometallic method and contain toxic elements, such as cadmium, lead, mercury, arsenic, etc. The overall goal of this thesis study is to develop an aqueous synthesis method to produce nontoxic quantum dots with strong emission and good stability, suitable for biomedical imaging applications.Firstly, an aqueous, simple, environmentally friendly synthesis method was developed. With cadmium sulfide (CdS) QDs as an example system, various processing parameters and capping molecules were examined to improve the synthesis and optimize the PL properties. The obtained water soluble QDs exhibited ultra small size (~5 nm), strong PL and good stability. Thereafter, using the aqueous method, the zinc sulfide (ZnS) QDs were synthesized with different capping molecules, i.e., 3-mercaptopropionic acid (MPA) and 3-(mercaptopropyl)trimethoxysilane (MPS). Especially, via a newly developed capping molecule replacement method, the present ZnS QDs exhibited bright blue emission with a quantum yield of 75% and more than 60 days lifetime in the ambient conditions. Two cytotoxicity tests with human endothelial cells verified the nontoxicity of the ZnS QDs by cell counting with Trypan blue staining and fluorescence assay with Alamar Blue. Taking advantage of the versatile surface chemistry, several strategies were explored to conjugate the water soluble QDs with biomolecules, i.e., antibody and streptavidin. Accordingly, the imaging of Salmonella t. cells and biotinylated microbeads has been successfully demonstrated. In addition, polyethylenimine (PEI)-QDs complex was formed and delivered into PC12 neuronal cells for intracellular i [...]
Cesium lead halide perovskite nanocrystals have a narrow emission peak tunable in the visible wav... more Cesium lead halide perovskite nanocrystals have a narrow emission peak tunable in the visible wavelength range with a high quantum yield. They hold great potential for optoelectronic applications such as light-emitting diodes or electronic displays. However, cesium lead iodide (CsPbI 3) is not stable under ambient conditions, limiting its applications. Here, we use a solution surface treatment approach to improve the photostability of CsPbI 3 suspensions in toluene. When a CsPbBr 3 precursor is used via the method of heterogeneous surface treatment, the photoluminescence (PL) intensity is enhanced but the PL only lasts 2 days. In contrast, when a CsPbI 3 precursor is used via the method of homogeneous surface treatment, not only the PL intensity of CsPbI 3 suspensions is enhanced but also the stability with the PL lasts for 11 days. It is likely that a better protection on the core CsPbI 3 by itself can be achieved because of better matching of the material structure and surface chemistry.
• Tin sulfide (SnS) quantum dots were surface treated with Zinc Sulfide (ZnS) precursors. • Surfa... more • Tin sulfide (SnS) quantum dots were surface treated with Zinc Sulfide (ZnS) precursors. • Surface treatment increased SnS QD photoluminescence by 20x without affecting emission wavelength. • Improved stability of SnS/ZnS QD suspensions in glycerol in a wide pH range with mercaptopropionic acid (MPA) • Improved stability of SnS/ZnS QD in aqueous suspensions using mercaptopropylsilane (MPS)
Current genetic detection methods require gene isolation, gene amplification and detection with a... more Current genetic detection methods require gene isolation, gene amplification and detection with a fluorescent-tagged probe. They typically require sophisticated equipment and expensive fluorescent probes, rendering them not widely available for rapid acute infection diagnoses at the point of care to ensure timely treatment of the diseases. Here we report a rapid genetic detection method that can detect the bacterial gene directly from patient stools using a piezoelectric plate sensor (PEPS) in conjunction with a continuous flow system with two temperature zones. With stools spiked with sodium dodecyl sulfate (SDS) in situ bacteria lysing and DNA denaturation occurred in the high-temperature zone whereas in situ specific detection of the denatured DNA by the PEPS occurred in the lower-temperature zone. The outcome was a rapid genetic detection 2 method that directly detected bacterial genes from stool in <40 min without the need of gene isolation, gene amplification, or expensive fluorescent tag but with polymerase chain reaction (PCR) sensitivity. In 40 blinded patient stools, it detected the toxin B gene of Clostridium difficile with 95% sensitivity and 95% specificity. The all-electrical, label-free nature of the detection further supports its potential as a low-cost genetic test that can be used at the point of care.
We have investigated amplification-free in situ double-stranded mutation detection in urine in th... more We have investigated amplification-free in situ double-stranded mutation detection in urine in the concentration range 10 M - 10 M using piezoelectric plate sensors (PEPs). The detection was carried out in a close-loop flow with two temperature zones. The 95 °C high-temperature zone served as the reservoir where the sample was loaded and DNA de-hybridized. The heated urine was cooled flowing through a 1 m long tubing immersed in room-temperature water bath at a flow rate of 4 ml/min to reach the detection cell at the desired temperature for the detection to take place. With hepatitis B virus double mutation (HBVDM) and KRAS G12V point mutation as model double mutations, it is shown that PEPS was able to detect double-stranded HBVDM and KRAS with 70% detection efficiency or better at concentration as low as 10 M against single-stranded mutation detection at the same concentrations, which was validated by the following in situ fluorescent reporter microspheres (FRMs) detection as wel...
Nanodesigning of multifunctional ceramic composites with colloids is discussed from a fundamental... more Nanodesigning of multifunctional ceramic composites with colloids is discussed from a fundamental point of view. We start with one-component systems, where packing density is the primary concern. Then we extend the discussion to binary systems and deal with the problem of homogeneity. We show that the structure is controlled by the nature of bonding between the particles and by the particle-particle interaction. Surfactants are used to modiy these properties, by, first, protecting the active particle surfaces to prevent solid bond formation, and, second, altering the interparticle interaction to provide a “lubricating” effect. In weakly attractive multicomponent systems, not only are we able to achieve high-density packing through restructuring, but we can also control the scale of homogeneity.
ABSTRACT We examined the effect of the boehmite coating thickness on the rheology and consolidati... more ABSTRACT We examined the effect of the boehmite coating thickness on the rheology and consolidation of boehmite-coated SiC suspensions. The thickness of the boehmite coating on SiC was varied by adjusting the boehmite concentration relative to SiC. For boehmite concentrations less than 10 wt%, the coating thickness increased with increasing boehmite concentration. For boehmite concentrations higher than 10 wt%, the coating thickness saturated. Further increase in the boehmite concentration led to the presence of small boehmite particles in the suspensions. All boehmite-coated suspensions gelled near their isoelectric points and the storage moduli of the gels with respect to pH exhibited a maximum near the isoelectric points. Below 10 wt% boehmite, the suspensions had very few small boehmite particles. The maximum storage modulus, G′0,max, of the boehmite-coated SiC gel decreased with increasing coating thickness, t, as G′0,max∝t−2, in good agreement with our earlier theoretical prediction. Meanwhile, the maximum sedimentation densities, φmax, of the coated suspensions occurred at around pH ∼ 4.0 and increased with increasing coating thickness from under φmax= 25 vol% with 1 wt% boehmite to above φmax= 65 vol% with 10 wt% boehmite due to increased zeta potential with increasing coating thickness. Above 10 wt% boehmite, the excess boehmite particles in the suspension increased the maximum suspension storage modulus, G′0,max, and decreased the maximum sedimentation density, φmax.
Aggregation of colloidal particles with a finite attraction energy was investigated with computer... more Aggregation of colloidal particles with a finite attraction energy was investigated with computer simulations and with gold particles coated with a surfactant. Computer simulations were carried out with the Shih-Aksay-Kikuchi (SAK) model, which incorporates a finite nearest-neighbor attraction energy-E into the diffusion-limited-cluster-aggregation (DLCA) model. Both the computer simulations and the experiments showed that (i) with a finite interparticle attraction energy, aggregates can still remain fractal, and (ii) the fractal dimension remains unchanged at large interparticle attraction energies and increases when the interparticle attraction energy is smaller than 4k~ T, where Tis the tcmperalurc and k. is the B~)ltzmann constant. The agrcemcnl between the simulations and the experimental results suggests that the reversiblc aggregation process in a colloidal system can be represented by the SAK model.
For piezoelectric microcantilever sensors (PEMSs) whose resonance frequency shift during detectio... more For piezoelectric microcantilever sensors (PEMSs) whose resonance frequency shift during detection is due to Young’s modulus change in the piezoelectric layer, we showed that their detection longitudinal flexural resonance frequency shift, Δf, is inversely proportional to the square of the PEMS length, L2; their relative resonance frequency shift, Δf/f, inversely proportional to the PEMS thickness, t; and their mass detection sensitivity, Δf/Δm, inversely proportional to wL3 where w is the width. The resonance frequency shift caused by Young’s modulus change in the piezoelectric layer is more than 300 times larger than would be expected from the mass change.
In this study, we examined how the materials’ properties of a lead magnesium niobate-lead titanat... more In this study, we examined how the materials’ properties of a lead magnesium niobate-lead titanate solid solution, [Pb(Mg1/3Nb2/3)O3]0.63[PbTiO3]0.37 (PMN-PT) piezoelectric plate sensor (PEPS) affected the enhancement of the relative detection resonance frequency shift, −Δf/f of the sensor, where f and Δf were the resonance frequency and resonance frequency shift of the sensor, respectively. Specifically, the electromechanical coupling constant, −k31, of the PMN-PT PEPS was varied by changing the grain size of the piezoelectric layer as well as by applying a bias direct current electric field. Detection of streptavidin at the same concentration was carried out with biotin covalently immobilized on the surface of PEPS. It is shown that the −Δf/f of the same streptavidin detection was increased by more than 2-fold when the −k31 increased from 0.285 to 0.391.
We have examined the in situ detection of a single-nucleotide KRAS mutation in urine using a (Pb(... more We have examined the in situ detection of a single-nucleotide KRAS mutation in urine using a (Pb(Mg1/3Nb2/3)O3)0.65(PbTiO3)0.35 (PMN-PT) piezoelectric plate sensor (PEPS) coated with a 17-nucleotide (nt) locked nucleic acid (LNA) probe DNA complementary to the KRAS mutation.
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Papers by Wan Y. Shih