The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform

Bryan A. Chin - One of the best experts on this subject based on the ideXlab platform.

  • Direct Detection of Bacterial Pathogens on Fresh Fruits and Vegetables
    2018 IEEE SENSORS, 2018
    Co-Authors: Shin Horikawa, Zhongyang Cheng, I-hsuan Chen, Xu Lu, Songtao Du, Yuzhe Liu, Tung-shi Huang, Bryan A. Chin
    Abstract:

    This paper presents a rapid method of detecting specific bacterial pathogens on the surface of fresh produce without sample preparation (water rinse, soak, stomaching) and/or enrichment. The method combines wireless, phage-coated magnetoelastic (ME) biosensors and a surface-scanning detector that can be passed over Food Surfaces for pathogen detection. The speed of detection is from 5 to 10 minutes. Simultaneous measurement of multiple sensors was demonstrated for the first time, which opens up the path to on-site, multiplexed pathogen detection.

  • Blocking Non-Specific Binding for Phage-Based Magnetoelastic Biosensors
    2015
    Co-Authors: Jiajia Hu, Shin Horikawa, Yating Chai, Bryan A. Chin, Jing Hu
    Abstract:

    The magnetoelastic (ME) biosensors are used to detect pathogen in fresh juice or milk by solenoid coil, and also developed for real-time, direct pathogen detection on Food Surfaces by surface-scanning coil. This paper presents blocking effect of different reagents on non-specific binding for detecting Salmonella typhimurium in apple juice using phage-based magnetoelastic biosensors. Three different blocking reagents of Bovine serum albumin, Superblock blocking buffer and blocker BLOTTO were used and evaluated. The results shows that blocker BLOTTO has the best blocking effect on non-specific binding.

  • In-situ detection of multiple pathogenic bacteria on Food Surfaces
    Proceedings of SPIE, 2015
    Co-Authors: Yating Chai, Shin Horikawa, Jiajia Hu, I-hsuan Chen, Jing Hu, James M. Barbaree, Bryan A. Chin
    Abstract:

    Real-time in-situ detection of pathogenic bacteria on fresh Food Surfaces was accomplished with phage-based magnetoelastic (ME) biosensors. The ME biosensor is constructed of a small rectangular strip of ME material that is coated with a biomolecular recognition element (phage, antibodies or proteins, etc.) that is specific to the target pathogen. This mass-sensitive ME biosensor is wirelessly actuated into mechanical resonance by an externally applied time-varying magnetic field. When the biosensor binds with target bacteria, the mass of the sensor increases, resulting in a decrease in the sensor's resonant frequency. In order to compensate for nonspecific binding, control biosensors without phage were used in this experiment. In previous research, the biosensors were measured one by one. However, the simultaneous measurement of multiple sensors was accomplished in this research, and promises to greatly shorten the analysis time for bacterial detection. Additionally, the use of multiple biosensors enables the possibility of simultaneous detection of different pathogenic bacteria. This paper presents results of experiments in which multiple phage-based ME biosensors were simultaneously monitored. The E2 phage and JRB7 phage from a landscape phage library served as the bio-recognition element that have the capability of binding specifically with Salmonella typhimurium and B. anthracis spores, respectively. Real-time in-situ detection of Salmonella typhimurium and B. anthracis spores on Food Surfaces are presented.

  • Effects of Food surface topography on phage-based magnetoelastic biosensor detection
    Proceedings of SPIE, 2014
    Co-Authors: Shin Horikawa, Yating Chai, Howard C. Wikle, Ruiting Zhao, Bryan A. Chin
    Abstract:

    Phage-based magnetoelastic (ME) biosensors have proven useful in rapidly and inexpensively detecting Food surface con- tamination. These biosensors are wireless, mass-sensitive biosensors and can be placed directly on Food Surfaces to detect the presence of target pathogens. Previously, millimeter-scale strip-shaped ME biosensors have been used to demonstrate direct detection of Salmonella Typhimurium on various fresh produce Surfaces, including tomatoes, shell eggs, watermel- ons, and spinach leaves. Since the topography of these produce Surfaces are different, and the biosensor must come into direct contact with Salmonella bacteria, Food Surfaces with large roughness and curvatures (e.g., spinach leaf Surfaces) may allow the bacteria to avoid direct contact, thereby avoiding detection. The primary objective of this paper is, hence, to investigate the effects of Food surface topography on the detection capabilities of the biosensors. Spinach leaf Surfaces were selected as model Surfaces, and detection experiments were conducted with differently sized biosensors (2 mm, 0.5 mm, and 150 μm in length). Spinach leaf roughness and curvatures of both adaxial (top) and abaxial (underside) Surfaces were measured using a confocal laser scanning microscope. The experimental results showed that in spinach as the sen- sor was made smaller, the physical contact between the biosensors and bacteria were improved. Smaller sensors thereby enhance detection capabilities. When proper numbers of biosensors are used, micron-scale biosensors are anticipated to yield improved limits of detection over previously investigated millimeter-scale biosensors.

  • a surface scanning coil detector for real time in situ detection of bacteria on fresh Food Surfaces
    Biosensors and Bioelectronics, 2013
    Co-Authors: Yating Chai, Shin Horikawa, Howard C. Wikle, Suiqiong Li, Bryan A. Chin
    Abstract:

    Abstract Proof-in-principle of a new surface-scanning coil detector has been demonstrated. This new coil detector excites and measures the resonant frequency of free-standing magnetoelastic (ME) biosensors that may now be placed outside the coil boundaries. With this coil design, the biosensors are no longer required to be placed inside the coil before frequency measurement. Hence, this new coil enables bacterial pathogens to be detected on fresh Food Surfaces in real-time and in-situ. The new coil measurement technique was demonstrated using an E2 phage-coated ME biosensor to detect Salmonella typhimurium on tomato Surfaces. Real-time, in-situ detection was achieved with a limit of detection (LOD) statistically determined to be lower than 1.5×103 CFU/mm2 with a confidence level of difference higher than 95% (p

Yating Chai - One of the best experts on this subject based on the ideXlab platform.

  • Blocking Non-Specific Binding for Phage-Based Magnetoelastic Biosensors
    2015
    Co-Authors: Jiajia Hu, Shin Horikawa, Yating Chai, Bryan A. Chin, Jing Hu
    Abstract:

    The magnetoelastic (ME) biosensors are used to detect pathogen in fresh juice or milk by solenoid coil, and also developed for real-time, direct pathogen detection on Food Surfaces by surface-scanning coil. This paper presents blocking effect of different reagents on non-specific binding for detecting Salmonella typhimurium in apple juice using phage-based magnetoelastic biosensors. Three different blocking reagents of Bovine serum albumin, Superblock blocking buffer and blocker BLOTTO were used and evaluated. The results shows that blocker BLOTTO has the best blocking effect on non-specific binding.

  • In-situ detection of multiple pathogenic bacteria on Food Surfaces
    Proceedings of SPIE, 2015
    Co-Authors: Yating Chai, Shin Horikawa, Jiajia Hu, I-hsuan Chen, Jing Hu, James M. Barbaree, Bryan A. Chin
    Abstract:

    Real-time in-situ detection of pathogenic bacteria on fresh Food Surfaces was accomplished with phage-based magnetoelastic (ME) biosensors. The ME biosensor is constructed of a small rectangular strip of ME material that is coated with a biomolecular recognition element (phage, antibodies or proteins, etc.) that is specific to the target pathogen. This mass-sensitive ME biosensor is wirelessly actuated into mechanical resonance by an externally applied time-varying magnetic field. When the biosensor binds with target bacteria, the mass of the sensor increases, resulting in a decrease in the sensor's resonant frequency. In order to compensate for nonspecific binding, control biosensors without phage were used in this experiment. In previous research, the biosensors were measured one by one. However, the simultaneous measurement of multiple sensors was accomplished in this research, and promises to greatly shorten the analysis time for bacterial detection. Additionally, the use of multiple biosensors enables the possibility of simultaneous detection of different pathogenic bacteria. This paper presents results of experiments in which multiple phage-based ME biosensors were simultaneously monitored. The E2 phage and JRB7 phage from a landscape phage library served as the bio-recognition element that have the capability of binding specifically with Salmonella typhimurium and B. anthracis spores, respectively. Real-time in-situ detection of Salmonella typhimurium and B. anthracis spores on Food Surfaces are presented.

  • Effects of Food surface topography on phage-based magnetoelastic biosensor detection
    Proceedings of SPIE, 2014
    Co-Authors: Shin Horikawa, Yating Chai, Howard C. Wikle, Ruiting Zhao, Bryan A. Chin
    Abstract:

    Phage-based magnetoelastic (ME) biosensors have proven useful in rapidly and inexpensively detecting Food surface con- tamination. These biosensors are wireless, mass-sensitive biosensors and can be placed directly on Food Surfaces to detect the presence of target pathogens. Previously, millimeter-scale strip-shaped ME biosensors have been used to demonstrate direct detection of Salmonella Typhimurium on various fresh produce Surfaces, including tomatoes, shell eggs, watermel- ons, and spinach leaves. Since the topography of these produce Surfaces are different, and the biosensor must come into direct contact with Salmonella bacteria, Food Surfaces with large roughness and curvatures (e.g., spinach leaf Surfaces) may allow the bacteria to avoid direct contact, thereby avoiding detection. The primary objective of this paper is, hence, to investigate the effects of Food surface topography on the detection capabilities of the biosensors. Spinach leaf Surfaces were selected as model Surfaces, and detection experiments were conducted with differently sized biosensors (2 mm, 0.5 mm, and 150 μm in length). Spinach leaf roughness and curvatures of both adaxial (top) and abaxial (underside) Surfaces were measured using a confocal laser scanning microscope. The experimental results showed that in spinach as the sen- sor was made smaller, the physical contact between the biosensors and bacteria were improved. Smaller sensors thereby enhance detection capabilities. When proper numbers of biosensors are used, micron-scale biosensors are anticipated to yield improved limits of detection over previously investigated millimeter-scale biosensors.

  • a surface scanning coil detector for real time in situ detection of bacteria on fresh Food Surfaces
    Biosensors and Bioelectronics, 2013
    Co-Authors: Yating Chai, Shin Horikawa, Howard C. Wikle, Suiqiong Li, Bryan A. Chin
    Abstract:

    Abstract Proof-in-principle of a new surface-scanning coil detector has been demonstrated. This new coil detector excites and measures the resonant frequency of free-standing magnetoelastic (ME) biosensors that may now be placed outside the coil boundaries. With this coil design, the biosensors are no longer required to be placed inside the coil before frequency measurement. Hence, this new coil enables bacterial pathogens to be detected on fresh Food Surfaces in real-time and in-situ. The new coil measurement technique was demonstrated using an E2 phage-coated ME biosensor to detect Salmonella typhimurium on tomato Surfaces. Real-time, in-situ detection was achieved with a limit of detection (LOD) statistically determined to be lower than 1.5×103 CFU/mm2 with a confidence level of difference higher than 95% (p

  • Surface-scanning coil detectors for magnetoelastic biosensors: A comparison of planar-spiral and solenoid coils
    Applied Physics Letters, 2013
    Co-Authors: Yating Chai, Shin Horikawa, Howard C. Wikle, Zhenyu Wang, Bryan A. Chin
    Abstract:

    This research introduces a planar spiral coil as a surface-scanning detector for magnetoelastic biosensors, which have been used to detect bacteria directly on Food Surfaces. The planar coil was compared with the previously investigated solenoid coil, in terms of the magnetic flux change, signal amplitude, and detection distance. Both theoretical calculations and experimental results demonstrated that the planar coil detector yields a dramatically improved signal amplitude and greater detection distance. In addition, simultaneous measurement of multiple biosensors on Surfaces was demonstrated. This planar coil is therefore anticipated to facilitate the detection of bacteria on Surfaces using magnetoelastic biosensors.

José Miguel Aguilera - One of the best experts on this subject based on the ideXlab platform.

  • Characterization of Food surface roughness using the glistening points method
    Journal of Food Engineering, 2004
    Co-Authors: Roberto Quevedo, José Miguel Aguilera
    Abstract:

    Abstract Several properties of Foods, most notably visual perception and color, depend on the complexity of their outer surface. The so-called glistening point method based on specular reflection of an incident light beam is a simple, non-invasive optical technique used to quantify the roughness of a surface. Assuming that a surface has a macroscopic random Gaussian roughness distribution, the method determines two parameters: the correlation length (L) and the rms amplitude (σ). Rougher Surfaces have higher L and σ values. Results show that the glistening point method is suitable for analysing Food Surfaces at the microscopic scale and is also useful to quantitatively follow changes in Food surface roughness as during chocolate blooming or after removal of the outer wax layer in fruits.

  • Characterization of Food surface roughness using the glistening points method
    Journal of Food Engineering, 2004
    Co-Authors: Roberto Quevedo, José Miguel Aguilera
    Abstract:

    Several properties of Foods, most notably visual perception and color, depend on the complexity of their outer surface. The so-called glistening point method based on specular reflection of an incident light beam is a simple, non-invasive optical technique used to quantify the roughness of a surface. Assuming that a surface has a macroscopic random Gaussian roughness distribution, the method determines two parameters: the correlation length (L) and the rms amplitude (σ). Rougher Surfaces have higher L and σ values. Results show that the glistening point method is suitable for analysing Food Surfaces at the microscopic scale and is also useful to quantitatively follow changes in Food surface roughness as during chocolate blooming or after removal of the outer wax layer in fruits. © 2003 Elsevier Ltd. All rights reserved.

  • description of Food Surfaces and microstructural changes using fractal image texture analysis
    Journal of Food Engineering, 2002
    Co-Authors: Roberto Quevedo, José Miguel Aguilera, Lopezg Carlos, Laura Cadoche
    Abstract:

    Images, particularly photomicrographs, provide qualitative information about Surfaces of Foods and cells. Methods to analyze the texture of images such as fractional Brownian motion (FBMM), box counting (BCM), and fractal dimension (FD) estimation from frequency domain (FDM), were used to numerically describe the Surfaces of Foods and the microstructure of potato cells. A FD was calculated for each image using the power-law scaling for self-similar fractals. The surface of analyzed Foods had FD varying from 2.22 for chocolate to 2.44 for pumpkin shell. As reference, the FD of sandpaper having increasing grain size or roughness varied from 2.37 to 2.65. FD was also useful to numerically describe microstructural changes with time of an isolated potato cell during heating in oil and of the surface of chocolate undergoing crystallization of fats (blooming).

  • characterization of Food Surfaces using scale sensitive fractal analysis
    Journal of Food Process Engineering, 2000
    Co-Authors: Franco Pedreschi, José Miguel Aguilera, Christopher A Brown
    Abstract:

    Length-scale and area-scale analyses, two of the scale-sensitive fractal analyses performed by the software Surfraxhttp://www.surfract.com, were used to study Food Surfaces measured with a scanning laser microscope (SLM). The SLM measures Surfaces, or textures (i.e., acquires topographical data as a collection of heights as a function of position), at a spatial and vertical resolution of 25 μm. The measured textures are analyzed by using linear and areal tiling (length-scale and area-scale analysis) and by conventional statistical analyses. Area-scale and length-scale fractal complexities (Lsfc and Asfc) and the smooth-rough crossover (SRC) are derived from the scale-sensitive fractal analyses. Both measures proved adequate to quantify and differentiate Surfaces of Foods (e.g., chocolate and a slice of bread), which were smooth or porous to the naked eye. Surfaces generated after frying of potato products (e.g., potato chips and French fries) had similar values of Asfc and SRC, and larger (implying more complex and rougher Surfaces) than those of the raw potato. Variability of surface texture characterization parameters as a function of the size of the measured region was used in selecting the size of the measured regions for further analysis. The length-scale method of profile analysis (also called the Richardson or compass method) was useful in determining the directionality or lay of the anisotropic texture on Food Surfaces.

  • CHARACTERIZATION OF Food Surfaces USING SCALE‐SENSITIVE FRACTAL ANALYSIS
    Journal of Food Process Engineering, 2000
    Co-Authors: Franco Pedreschi, José Miguel Aguilera, Christopher A Brown
    Abstract:

    Length-scale and area-scale analyses, two of the scale-sensitive fractal analyses performed by the software Surfraxhttp://www.surfract.com, were used to study Food Surfaces measured with a scanning laser microscope (SLM). The SLM measures Surfaces, or textures (i.e., acquires topographical data as a collection of heights as a function of position), at a spatial and vertical resolution of 25 μm. The measured textures are analyzed by using linear and areal tiling (length-scale and area-scale analysis) and by conventional statistical analyses. Area-scale and length-scale fractal complexities (Lsfc and Asfc) and the smooth-rough crossover (SRC) are derived from the scale-sensitive fractal analyses. Both measures proved adequate to quantify and differentiate Surfaces of Foods (e.g., chocolate and a slice of bread), which were smooth or porous to the naked eye. Surfaces generated after frying of potato products (e.g., potato chips and French fries) had similar values of Asfc and SRC, and larger (implying more complex and rougher Surfaces) than those of the raw potato. Variability of surface texture characterization parameters as a function of the size of the measured region was used in selecting the size of the measured regions for further analysis. The length-scale method of profile analysis (also called the Richardson or compass method) was useful in determining the directionality or lay of the anisotropic texture on Food Surfaces.

Shin Horikawa - One of the best experts on this subject based on the ideXlab platform.

  • Direct Detection of Bacterial Pathogens on Fresh Fruits and Vegetables
    2018 IEEE SENSORS, 2018
    Co-Authors: Shin Horikawa, Zhongyang Cheng, I-hsuan Chen, Xu Lu, Songtao Du, Yuzhe Liu, Tung-shi Huang, Bryan A. Chin
    Abstract:

    This paper presents a rapid method of detecting specific bacterial pathogens on the surface of fresh produce without sample preparation (water rinse, soak, stomaching) and/or enrichment. The method combines wireless, phage-coated magnetoelastic (ME) biosensors and a surface-scanning detector that can be passed over Food Surfaces for pathogen detection. The speed of detection is from 5 to 10 minutes. Simultaneous measurement of multiple sensors was demonstrated for the first time, which opens up the path to on-site, multiplexed pathogen detection.

  • Blocking Non-Specific Binding for Phage-Based Magnetoelastic Biosensors
    2015
    Co-Authors: Jiajia Hu, Shin Horikawa, Yating Chai, Bryan A. Chin, Jing Hu
    Abstract:

    The magnetoelastic (ME) biosensors are used to detect pathogen in fresh juice or milk by solenoid coil, and also developed for real-time, direct pathogen detection on Food Surfaces by surface-scanning coil. This paper presents blocking effect of different reagents on non-specific binding for detecting Salmonella typhimurium in apple juice using phage-based magnetoelastic biosensors. Three different blocking reagents of Bovine serum albumin, Superblock blocking buffer and blocker BLOTTO were used and evaluated. The results shows that blocker BLOTTO has the best blocking effect on non-specific binding.

  • In-situ detection of multiple pathogenic bacteria on Food Surfaces
    Proceedings of SPIE, 2015
    Co-Authors: Yating Chai, Shin Horikawa, Jiajia Hu, I-hsuan Chen, Jing Hu, James M. Barbaree, Bryan A. Chin
    Abstract:

    Real-time in-situ detection of pathogenic bacteria on fresh Food Surfaces was accomplished with phage-based magnetoelastic (ME) biosensors. The ME biosensor is constructed of a small rectangular strip of ME material that is coated with a biomolecular recognition element (phage, antibodies or proteins, etc.) that is specific to the target pathogen. This mass-sensitive ME biosensor is wirelessly actuated into mechanical resonance by an externally applied time-varying magnetic field. When the biosensor binds with target bacteria, the mass of the sensor increases, resulting in a decrease in the sensor's resonant frequency. In order to compensate for nonspecific binding, control biosensors without phage were used in this experiment. In previous research, the biosensors were measured one by one. However, the simultaneous measurement of multiple sensors was accomplished in this research, and promises to greatly shorten the analysis time for bacterial detection. Additionally, the use of multiple biosensors enables the possibility of simultaneous detection of different pathogenic bacteria. This paper presents results of experiments in which multiple phage-based ME biosensors were simultaneously monitored. The E2 phage and JRB7 phage from a landscape phage library served as the bio-recognition element that have the capability of binding specifically with Salmonella typhimurium and B. anthracis spores, respectively. Real-time in-situ detection of Salmonella typhimurium and B. anthracis spores on Food Surfaces are presented.

  • Effects of Food surface topography on phage-based magnetoelastic biosensor detection
    Proceedings of SPIE, 2014
    Co-Authors: Shin Horikawa, Yating Chai, Howard C. Wikle, Ruiting Zhao, Bryan A. Chin
    Abstract:

    Phage-based magnetoelastic (ME) biosensors have proven useful in rapidly and inexpensively detecting Food surface con- tamination. These biosensors are wireless, mass-sensitive biosensors and can be placed directly on Food Surfaces to detect the presence of target pathogens. Previously, millimeter-scale strip-shaped ME biosensors have been used to demonstrate direct detection of Salmonella Typhimurium on various fresh produce Surfaces, including tomatoes, shell eggs, watermel- ons, and spinach leaves. Since the topography of these produce Surfaces are different, and the biosensor must come into direct contact with Salmonella bacteria, Food Surfaces with large roughness and curvatures (e.g., spinach leaf Surfaces) may allow the bacteria to avoid direct contact, thereby avoiding detection. The primary objective of this paper is, hence, to investigate the effects of Food surface topography on the detection capabilities of the biosensors. Spinach leaf Surfaces were selected as model Surfaces, and detection experiments were conducted with differently sized biosensors (2 mm, 0.5 mm, and 150 μm in length). Spinach leaf roughness and curvatures of both adaxial (top) and abaxial (underside) Surfaces were measured using a confocal laser scanning microscope. The experimental results showed that in spinach as the sen- sor was made smaller, the physical contact between the biosensors and bacteria were improved. Smaller sensors thereby enhance detection capabilities. When proper numbers of biosensors are used, micron-scale biosensors are anticipated to yield improved limits of detection over previously investigated millimeter-scale biosensors.

  • a surface scanning coil detector for real time in situ detection of bacteria on fresh Food Surfaces
    Biosensors and Bioelectronics, 2013
    Co-Authors: Yating Chai, Shin Horikawa, Howard C. Wikle, Suiqiong Li, Bryan A. Chin
    Abstract:

    Abstract Proof-in-principle of a new surface-scanning coil detector has been demonstrated. This new coil detector excites and measures the resonant frequency of free-standing magnetoelastic (ME) biosensors that may now be placed outside the coil boundaries. With this coil design, the biosensors are no longer required to be placed inside the coil before frequency measurement. Hence, this new coil enables bacterial pathogens to be detected on fresh Food Surfaces in real-time and in-situ. The new coil measurement technique was demonstrated using an E2 phage-coated ME biosensor to detect Salmonella typhimurium on tomato Surfaces. Real-time, in-situ detection was achieved with a limit of detection (LOD) statistically determined to be lower than 1.5×103 CFU/mm2 with a confidence level of difference higher than 95% (p

Howard C. Wikle - One of the best experts on this subject based on the ideXlab platform.

  • Magnetoelastic sensors for high throughput screening of pathogens in Food
    High Throughput Screening for Food Safety Assessment, 2014
    Co-Authors: S. Li, Howard C. Wikle, B.a. Chin
    Abstract:

    This chapter introduces freestanding, phage-based magnetoelastic (ME) biosensors and their applications as a label-free wireless method for real-time pathogen detection. The ME biosensor is composed of an ME resonator that is coated with a biomolecular recognition element that binds specifically with a target pathogen. Interrogated through magnetic signals, ME biosensors can provide real-time, remote, and specific detection of Foodborne pathogens in water, buffer, liquid Food, and Food Surfaces. This chapter introduces the detection principle, the interrogation system, the fabrication of ME biosensors, and their current and future applications in high throughput screening of pathogens in Food.

  • Effects of Food surface topography on phage-based magnetoelastic biosensor detection
    Proceedings of SPIE, 2014
    Co-Authors: Shin Horikawa, Yating Chai, Howard C. Wikle, Ruiting Zhao, Bryan A. Chin
    Abstract:

    Phage-based magnetoelastic (ME) biosensors have proven useful in rapidly and inexpensively detecting Food surface con- tamination. These biosensors are wireless, mass-sensitive biosensors and can be placed directly on Food Surfaces to detect the presence of target pathogens. Previously, millimeter-scale strip-shaped ME biosensors have been used to demonstrate direct detection of Salmonella Typhimurium on various fresh produce Surfaces, including tomatoes, shell eggs, watermel- ons, and spinach leaves. Since the topography of these produce Surfaces are different, and the biosensor must come into direct contact with Salmonella bacteria, Food Surfaces with large roughness and curvatures (e.g., spinach leaf Surfaces) may allow the bacteria to avoid direct contact, thereby avoiding detection. The primary objective of this paper is, hence, to investigate the effects of Food surface topography on the detection capabilities of the biosensors. Spinach leaf Surfaces were selected as model Surfaces, and detection experiments were conducted with differently sized biosensors (2 mm, 0.5 mm, and 150 μm in length). Spinach leaf roughness and curvatures of both adaxial (top) and abaxial (underside) Surfaces were measured using a confocal laser scanning microscope. The experimental results showed that in spinach as the sen- sor was made smaller, the physical contact between the biosensors and bacteria were improved. Smaller sensors thereby enhance detection capabilities. When proper numbers of biosensors are used, micron-scale biosensors are anticipated to yield improved limits of detection over previously investigated millimeter-scale biosensors.

  • a surface scanning coil detector for real time in situ detection of bacteria on fresh Food Surfaces
    Biosensors and Bioelectronics, 2013
    Co-Authors: Yating Chai, Shin Horikawa, Howard C. Wikle, Suiqiong Li, Bryan A. Chin
    Abstract:

    Abstract Proof-in-principle of a new surface-scanning coil detector has been demonstrated. This new coil detector excites and measures the resonant frequency of free-standing magnetoelastic (ME) biosensors that may now be placed outside the coil boundaries. With this coil design, the biosensors are no longer required to be placed inside the coil before frequency measurement. Hence, this new coil enables bacterial pathogens to be detected on fresh Food Surfaces in real-time and in-situ. The new coil measurement technique was demonstrated using an E2 phage-coated ME biosensor to detect Salmonella typhimurium on tomato Surfaces. Real-time, in-situ detection was achieved with a limit of detection (LOD) statistically determined to be lower than 1.5×103 CFU/mm2 with a confidence level of difference higher than 95% (p

  • Surface-scanning coil detectors for magnetoelastic biosensors: A comparison of planar-spiral and solenoid coils
    Applied Physics Letters, 2013
    Co-Authors: Yating Chai, Shin Horikawa, Howard C. Wikle, Zhenyu Wang, Bryan A. Chin
    Abstract:

    This research introduces a planar spiral coil as a surface-scanning detector for magnetoelastic biosensors, which have been used to detect bacteria directly on Food Surfaces. The planar coil was compared with the previously investigated solenoid coil, in terms of the magnetic flux change, signal amplitude, and detection distance. Both theoretical calculations and experimental results demonstrated that the planar coil detector yields a dramatically improved signal amplitude and greater detection distance. In addition, simultaneous measurement of multiple biosensors on Surfaces was demonstrated. This planar coil is therefore anticipated to facilitate the detection of bacteria on Surfaces using magnetoelastic biosensors.

  • Design of a surface-scanning coil detector for direct bacteria detection on Food Surfaces using a magnetoelastic biosensor
    Journal of Applied Physics, 2013
    Co-Authors: Yating Chai, Zhongyang Cheng, Dave F. Dyer, Steve Best, Shin Horikawa, Howard C. Wikle, Zhenyu Wang, Bryan A. Chin
    Abstract:

    The real-time, in-situ bacteria detection on Food Surfaces was achieved by using a magnetoelastic biosensor combined with a surface-scanning coil detector. This paper focuses on the coil design for signal optimization. The coil was used to excite the sensor's vibration and detect its resonant frequency signal. The vibrating sensor creates a magnetic flux change around the coil, which then produces a mutual inductance. In order to enhance the signal amplitude, a theory of the sensor's mutual inductance with the measurement coil is proposed. Both theoretical calculations and experimental data showed that the working length of the coil has a significant effect on the signal amplitude. For a 1 mm-long sensor, a coil with a working length of 1.3 mm showed the best signal amplitude. The real-time detection of Salmonella bacteria on a fresh Food surface was demonstrated using this new technology. © 2013 AIP Publishing LLC