High-Sensitivity MEMS Resonant Biosensor for Monitoring Water Toxicity

2017 ◽  
Author(s):  
Kun-Lin Lee ◽  
Simon Ng ◽  
Fang Li ◽  
Ioana Voiculescu
Keyword(s):  
Resonant Frequency ◽  
Quartz Crystal ◽  
High Sensitivity ◽  
Live Cells ◽  
Toxicity Tests ◽  
Piezoelectric Resonator ◽  
Sensitivity Testing ◽  
Water Toxicity ◽  
Water Based ◽  
Trout Gill

This paper presents the use of a piezoelectric resonator, which can be applied to investigate live cells activity in water-based toxic solution. We perform toxicity tests using commercial quartz crystal microbalance (QCM). The QCM used in this research has the resonant frequency of 10 MHz and consists in an AT-cut crystal with gold electrodes on both sides. This QCM was transformed into a functional biosensor by integrating with polydimethylsiloxane (PDMS) culturing chambers. Rainbow trout gill epithelial cells (RTgill-W1) were cultured on the resonators as sensorial layer. The fluctuation of the resonant frequency, due to the change of cell morphology and adhesion, is an indicator of water toxicity. The shift of resonant frequency will provide information about the cells viability after exposure to toxicants. Experiment setup, fabrication process, and sensor sensitivity testing are addressed. The toxicity result shows distinct responses for different ammonia concentrations.

High Sensitivity MEMS Biosensor for Monitoring Cell Attachment

2012 ◽  
Author(s):  
Fei Liu ◽  
Fang Li ◽  
David C. Spray ◽  
Anis Nurashikin Nordin ◽  
Ioana Voiculescu
Keyword(s):  
Resonant Frequency ◽  
Cell Attachment ◽  
High Sensitivity ◽  
Live Cells ◽  
Seeding Density ◽  
Impedance Sensing ◽  
Aortic Endothelial Cells ◽  
Frequency Measurements ◽  
Cell Substrate ◽  
Time Required

This paper presents the fabrication and testing of a novel microelectromechanical (MEMS) biosensor based on live cells. The biosensor combines two biosensing techniques; resonant frequency measurements and electric cell-substrate impedance sensing (ECIS) on a single device. The sensor is based on the innovative placement of the working microelectrode for ECIS technique as the upper electrode of a quartz crystal microbalance (QCM) resonator. This hybrid biosensor was tested with bovine aortic endothelial cells with different seeding densities. The cell attachment and spreading was monitored with both sensors; the QCM and the ECIS technique. After the cells form a monolayer the values of the impedance and resonant frequency measurements are constant. The optimal cell seeding density with minimal time required to attach and form a monolayer was observed to be 1.5×104 cells/cm2. This biosensor monitors the cells attachment and viability and could be used for screening toxicants in drinking water.

Study of Long Term Viability of Endothelial Cells on Biochip for Rapid and Reliable Water Toxicity Measurements

2013 ◽  
Author(s):  
Fei Liu ◽  
Tingting Chen ◽  
Xudong Zhang ◽  
Fang Li ◽  
Ioana Voiculescu
Keyword(s):  
Shear Stress ◽  
Microfluidic Device ◽  
Cell Attachment ◽  
Good Health ◽  
Low Flow ◽  
Live Cells ◽  
Toxicity Tests ◽  
Bovine Aortic Endothelial Cell ◽  
Microfluidic Channels ◽  
Water Toxicity

Measuring water toxicity is a lengthy process, and rapid analytical methods are limited. A complementary approach is to measure water toxicity on live cells via electric cell-substrate impedance sensing (ECIS) using a field portable device. This paper presents a study of the longevity of bovine aortic endothelial cell (BAECs VEC Technologies, Rensselaer, NY) by integrating a microfluidic device onto the ECIS sensors. This microfluidic chamber with a network of tree-like perfusion microfluidic channels for cell media delivery to the culturing chamber was fabricated from a biocompatible polymer and tested for longevity studies. This perfusion microchannels were designed as a symmetric arbor with binary splitting to provide equal flow in all the perfusion channels. The microdimensions of the perfusion channels provide high flow resistance, thus carrying low flow rates for a given head pressure and generating low shear stress to the cells during the long-time cell attachment and proliferation period. With such a microfluidic device, cell media can be automatically and evenly perfused into the culturing chamber and no significant shear stress produced by media perfusion was observed. During the longevity study, the BAECs were able to survive in good health for longer than one month. Toxicity tests to study the BAECs responsiveness to health-threatening concentrations of ammonia using the microfluidic ECIS sensor will be also presented. Using impedance spectroscopy technique we demonstrated the BAECs can rapidly respond to ammonia concentrations between the military exposure guideline of 2mM and human lethal concentration of 55mM. The BAECs monolayer represent the most important component of a biosensor for testing water toxicity in the field. This research concluded that the BAECs could resist at least 34 days on the microfluidic chip and demonstrate high values of cell membrane impedance during long period of time.

scholarly journals Fluorescent Probes for Live Cell Thiol Detection

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3575
Author(s):  
Shenggang Wang ◽  
Yue Huang ◽  
Xiangming Guan
Keyword(s):  
Fluorescent Probes ◽  
Biological System ◽  
High Sensitivity ◽  
Intracellular Distribution ◽  
Live Cell ◽  
Live Cells ◽  
High Demand ◽  
Non Invasive

Thiols play vital and irreplaceable roles in the biological system. Abnormality of thiol levels has been linked with various diseases and biological disorders. Thiols are known to distribute unevenly and change dynamically in the biological system. Methods that can determine thiols’ concentration and distribution in live cells are in high demand. In the last two decades, fluorescent probes have emerged as a powerful tool for achieving that goal for the simplicity, high sensitivity, and capability of visualizing the analytes in live cells in a non-invasive way. They also enable the determination of intracellular distribution and dynamitic movement of thiols in the intact native environments. This review focuses on some of the major strategies/mechanisms being used for detecting GSH, Cys/Hcy, and other thiols in live cells via fluorescent probes, and how they are applied at the cellular and subcellular levels. The sensing mechanisms (for GSH and Cys/Hcy) and bio-applications of the probes are illustrated followed by a summary of probes for selectively detecting cellular and subcellular thiols.

scholarly journals Alcohol-based highly conductive polymer for conformal nanocoatings on hydrophobic surfaces toward a highly sensitive and stable pressure sensor

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Jung Joon Lee ◽  
Srinivas Gandla ◽  
Byeongjae Lim ◽  
Sunju Kang ◽  
Sunyoung Kim ◽  
...  
Keyword(s):  
Pressure Sensor ◽  
Mechanical Stability ◽  
Exchange Process ◽  
Conductive Polymer ◽  
High Sensitivity ◽  
Fast Response ◽  
Pdms Surface ◽  
Practical Applications ◽  
Sensor Applications ◽  
Water Based

Abstract Conformal and ultrathin coating of highly conductive PEDOT:PSS on hydrophobic uneven surfaces is essential for resistive-based pressure sensor applications. For this purpose, a water-based poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) solution was successfully exchanged to an organic solvent-based PEDOT:PSS solution without any aggregation or reduction in conductivity using the ultrafiltration method. Among various solvents, the ethanol (EtOH) solvent-exchanged PEDOT:PSS solution exhibited a contact angle of 34.67°, which is much lower than the value of 96.94° for the water-based PEDOT:PSS solution. The optimized EtOH-based PEDOT:PSS solution exhibited conformal and uniform coating, with ultrathin nanocoated films obtained on a hydrophobic pyramid polydimethylsiloxane (PDMS) surface. The fabricated pressure sensor showed high performances, such as high sensitivity (−21 kPa−1 in the low pressure regime up to 100 Pa), mechanical stability (over 10,000 cycles without any failure or cracks) and a fast response time (90 ms). Finally, the proposed pressure sensor was successfully demonstrated as a human blood pulse rate sensor and a spatial pressure sensor array for practical applications. The solvent exchange process using ultrafiltration for these applications can be utilized as a universal technique for improving the coating property (wettability) of conducting polymers as well as various other materials.

scholarly journals Complex Permittivity Characterization of Liquid Samples Based on a Split Ring Resonator (SRR)

Sensors ◽  
2021 ◽  
Vol 21 (10) ◽  
pp. 3385
Author(s):  
Jialu Ma ◽  
Jingchao Tang ◽  
Kaicheng Wang ◽  
Lianghao Guo ◽  
Yubin Gong ◽  
...  
Keyword(s):  
Resonant Frequency ◽  
Complex Permittivity ◽  
Ring Resonator ◽  
High Sensitivity ◽  
Split Ring Resonator ◽  
Debye Model ◽  
Split Ring ◽  
Liquid Samples ◽  
Microwave Sensor

A complex permittivity characterization method for liquid samples has been proposed. The measurement is carried out based on a self-designed microwave sensor with a split ring resonator (SRR), the unload resonant frequency of which is 5.05 GHz. The liquid samples in capillary are placed in the resonant zone of the fabricated senor for high sensitivity measurement. The frequency shift of 58.7 MHz is achieved when the capillary is filled with ethanol, corresponding a sensitivity of 97.46 MHz/μL. The complex permittivity of methanol, ethanol, isopropanol (IPA) and deionized water at the resonant frequency are measured and calibrated by the first order Debye model. Then, the complex permittivity of different concentrations of aqueous solutions of these materials are measured by using the calibrated sensor system. The results show that the proposed sensor has high sensitivity and accuracy in measuring the complex permittivity of liquid samples with volumes as small as 0.13 μL. It provides a useful reference for the complex permittivity characterization of small amount of liquid chemical samples. In addition, the characterization of an important biological sample (inositol) is carried out by using the proposed sensor.

Recent advances in nanomaterial-based luminescent ATP sensors

2021 ◽  
Vol 17 ◽  
Author(s):  
Xiaomeng Zhou ◽  
Li Shang
Keyword(s):  
Carbon Nanomaterials ◽  
Metal Organic Frameworks ◽  
High Sensitivity ◽  
Live Cells ◽  
Biological Processes ◽  
Future Prospects ◽  
Advantages And Disadvantages ◽  
Sensitivity And Selectivity ◽  
Metal Organic ◽  
Atp Sensing

: Adenosine 5'-triphosphate (ATP) plays a significant role in biological processes and the ATP level is closely associated with many diseases. In order to detect ATP in live cells, tissues and body fluids with a high sensitivity and selectivity, researchers have developed various sensing strategies. Particularly, owing to distinct physicochemical properties of nanomaterials and high sensitivity of fluorescence, a great deal of efforts have been devoted to developing nanomaterials-based approaches for fluorescent ATP sensing in recent years. In this review, we focus on the current development of nanomaterial-based fluorescent ATP sensors and discuss the sensing mechanisms in detail. The advantages and disadvantages of ATP sensing using different kinds of nanomaterials, including carbon nanomaterials, metal nanoparticles, semiconductor quantum dots, metal-organic frameworks and up-conversion nanoparticles have been thoroughly compared and discussed. Finally, current challenges and future prospects in this field are given.

Resonant frequency of a piezoelectric quartz crystal in contact with solutions

1993 ◽  
Vol 274 (2) ◽  
pp. 209-217 ◽  
Author(s):  
Shigeru Kurosawa ◽  
Hideo Kitajima ◽  
Yoshihiko Ogawa ◽  
Makoto Muratsugu ◽  
Eiji Nemoto ◽  
...  
Keyword(s):  
Resonant Frequency ◽  
Quartz Crystal ◽  
Piezoelectric Quartz ◽  
Piezoelectric Quartz Crystal
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