A micro-scale multi-frequency reactance measurement technique to detect bacterial growth at low bio-particle concentrations

Sengupta, Shramik; Battigelli, David A.; Chang, Hsueh‐Chia

doi:10.1039/b516274b

Cited by 38 publications

(41 citation statements)

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“…To help overcome this, one group has successfully measured bacterial growth through changes in the bulk capacitance at low frequencies ͑below 1 MHz͒ by confining samples within long narrow geometries, which enhance the bulk resistance and hence the sensitivity to bulk capacitance. 17 Furthermore, capacitance-based sensing systems integrated into gyroscopes have achieved 12 zeptoFarad ͑zF͒ resolution. 18 If sensors of this sensitivity were combined with microfluidic systems for transporting cells, highly integrated diagnostic systems would be possible.…”

Section: Introductionmentioning

confidence: 99%

“…We use high frequencies ͑GHz͒ for capacitance measurements to avoid interference and variability due to effects such as electrical double layers, 6,17,19 ionic conduction, and other forms of dielectric variation in materials with frequency, which are dominant at frequencies below 200 MHz. 20 The use of high frequencies also opens the door for lower frequencies ͑MHz͒ to be used for other purposes such as simultaneous electromanipulation of biological materials.…”

Section: Introductionmentioning

confidence: 99%

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Microfluidic electromanipulation with capacitive detection for the mechanical analysis of cells

et al. 2008

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The mechanical behavior of cells offers insight into many aspects of their properties. We propose an approach to the mechanical analysis of cells that uses a combination of electromanipulation for stimulus and capacitance for sensing. To demonstrate this approach, polystyrene spheres and yeast cells flowing in a 25 m ϫ 100 m microfluidic channel were detected by a perpendicular pair of gold thin film electrodes in the channel, spaced 25 m apart. The presence of cells was detected by capacitance changes between the gold electrodes. The capacitance sensor was a resonant coaxial radio frequency cavity ͑2.3 GHz͒ coupled to the electrodes. The presence of yeast cells ͑Saccharomyces cerevisiae͒ and polystyrene spheres resulted in capacitance changes of approximately 10 and 100 attoFarad ͑aF͒, respectively, with an achieved capacitance resolution of less than 2 aF in a 30 Hz bandwidth. The resolution is better than previously reported in the literature, and the capacitance changes are in agreement with values estimated by finite element simulations. Yeast cells were trapped using dielectrophoretic forces by applying a 3 V signal at 1 MHz between the electrodes. After trapping, the cells were displaced using amplitude and frequency modulated voltages to produce modulated dielectrophoretic forces. Repetitive displacement and relaxation of these cells was observed using both capacitance and video microscopy.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Microfluidic electromanipulation with capacitive detection for the mechanical analysis of cells

et al. 2008

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“…Cell growth curves of E. faecalis with different concentrations of amoxicillin were monitored by this sensor system, showing the growth inhibition of the bacterial cells by antibiotic amoxicillin at 8 mg/l. The miniaturized biosensor gets the results in less than 2 h, in comparison to the standard test that can get the result after 6 h. Sengupta et al (2006) developed a micro-scale multifrequency reactance measurement technique to detect bacterial growth. They designed a micro-capillary to increase the bulk resistance (R) of the medium, thus increasing its RC time constant.…”

Section: Microchips For Impedance Detection Of Bacteriamentioning

confidence: 99%

Food‐borne Pathogenic Bacteria

Shi

Xie

Zhou

2017

Food Safety in China

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The realization of rapid, sensitive, and specific methods to detect foodborne pathogenic bacteria is central to implementing effective practice to ensure food safety and security. As a principle of transduction, the impedance technique has been applied in the field of microbiology as a means to detect and/or quantify foodborne pathogenic bacteria. The integration of impedance with biological recognition technology for detection of bacteria has led to the development of impedance biosensors that are finding wide-spread use in the recent years. This paper reviews the progress and applications of impedance microbiology for foodborne pathogenic bacteria detection, particularly the new aspects that have been added to this subject in the past few years, including the use of interdigitated microelectrodes, the development of chip-based impedance microbiology, and the use of equivalent circuits for analysis of the impedance systems. This paper also reviews the significant developments of impedance biosensors for bacteria detection in the past 5 years, focusing on microfabricated microelectrodes-based and microfluidic-based Faradaic electrochemical impedance biosensors, non-Faradaic impedance biosensors, and the integration of impedance biosensors with other techniques such as dielectrophoresis and electropermeabilization. Published by Elsevier Inc.

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“…Aqueous solutions containing such viable cells can be electrically modeled by a circuit, one of whose elements (the bulk capacitance) reflects the amount of charge stored by elements dispersed in the interior of the suspension (as opposed to the electrode-solution interface, where most of the charge is typically stored) (11). One can estimate the value of the bulk capacitance by measuring the electrical impedance (Z) at a number of frequencies () and fitting the Z-versus-data to a mathematical model of the circuit (10). If the number of viable bacteria increases, so does the bulk capacitance value.…”

mentioning

confidence: 99%

“…A significant increase in CO 2 is taken to indicate the presence of viable bacteria in the suspension and hence in blood. Due to inherent limitations imposed by the metabolic rate of individual bacterial cells (e.g., one Escherichia coli bacterium consumes only ϳ2 ϫ 10 Ϫ14 moles of O 2 per hour [10]), the concentrations of bacteria in the suspension typically have to rise to ϳ10 8 CFU/ml before they can be detected (12). Given the low initial loads, this implies that 20 to 30 doubling times must elapse before the bacteria can be detected, resulting in the long TTPs (12 to 72 h) typically observed.…”

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confidence: 99%

Novel Electrical Method for Early Detection of Viable Bacteria in Blood Cultures

2011

Self Cite

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We present a novel electrical method for detecting viable bacteria in blood cultures that is 4 to 10 times faster than continuous monitoring blood culture systems (CMBCS) like the Bactec system. Proliferating bacteria are detected via an increase in the bulk capacitance of suspensions, and the threshold concentration for detection is ϳ10 4 CFU/ml (compared to ϳ10 8 CFU/ml for the Bactec system).Continuous monitoring blood culture systems (CMBCS), like the Bactec, BacT/Alert, and VersaTREK systems, currently serve as the "gold standard" for the detection of bacteremia and sepsis in the clinical setting. Blood cultures typically take between 12 and 72 h to yield positive results (3-5) and are usually continued for 120 h (5 days) before being deemed negative. For positive cultures, bacteria present are then identified (using various methods, ranging from traditional biochemical tests to PCR-based DNA analysis, that take an additional 3 to 24 h) before targeted antibiotics are administered. For every hour of delay in starting targeted antibiotic therapy, the risk of death for a given patient with sepsis increases by 6 to 10% (6). Since the blood culture step is by far the longer of the two diagnostic steps needed, cutting down the times to positivity (TTPs) of blood cultures is likely to reduce mortality and improve patient outcomes.At the time the patient begins to show clinical symptoms of sepsis, the concentration of bacteria present in blood is very low (1 to 100 CFU/ml in adults [13] and Ͻ10 CFU/ml in neonates [9]). Currently available CMBCS (like the Bactec, BacT/Alert, and VersaTREK systems) require the user to introduce the drawn blood (ϳ10 ml for adults and ϳ1 ml for neonates) into a bottle containing 20 to 40 ml of sterile bacterial growth medium and place it in a special incubation chamber. Here, the CMBCS monitor the levels of CO 2 in the suspension. A significant increase in CO 2 is taken to indicate the presence of viable bacteria in the suspension and hence in blood. Due to inherent limitations imposed by the metabolic rate of individual bacterial cells (e.g., one Escherichia coli bacterium consumes only ϳ2 ϫ 10

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A micro-scale multi-frequency reactance measurement technique to detect bacterial growth at low bio-particle concentrations

Cited by 38 publications

References 23 publications

Microfluidic electromanipulation with capacitive detection for the mechanical analysis of cells

Microfluidic electromanipulation with capacitive detection for the mechanical analysis of cells

Food‐borne Pathogenic Bacteria

Novel Electrical Method for Early Detection of Viable Bacteria in Blood Cultures

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