http://cau.ac.kr/~jjang14/BioMEMS/Ivnitski_BSBE_Bacteria_Detection_Bio_Sensors_Review_1999.pdf

Biosensors for detection of pathogenic bacteria

In the early days of electronic communication-as a result of the limited number of quartz resonators available-frequency adjustment was accomplished by a pencil mark depositing a foreign mass layer on the crystal. In 1959, Sauerbrey showed that the shift in resonance frequency of thickness-shear-mode resonators is proportional to the deposited mass. This was the starting point for the development of a new generation of piezoelectric mass-sensitive devices. However, it was the development of new powerful oscillator circuits that were capable of operating thickness shear mode resonators in fluids that enabled this technique to be introduced into bioanalytic applications. In the last decade adsorption of biomolecules on functionalized surfaces turned in to one of the paramount applications of piezoelectric transducers. These applications include the study of the interaction of DNA and RNA with complementary strands, specific recognition of protein ligands by immobilized receptors, the detection of virus capsids, bacteria, mammalian cells, and last but not least the development of complete immunosensors. Piezoelectric transducers allow a label-free detection of molecules; they are more than mere mass sensors since the sensor response is also influenced by interfacial phenomena, viscoelastic properties of the adhered biomaterial, surface charges of adsorbed molecules, and surface roughness. These new insights have recently been used to investigate the adhesion of cells, liposomes, and proteins onto surfaces, thus allowing the determination of the morphological changes of cells as a response to pharmacological substances and changes in the water content of biopolymers without employing labor-intense techniques. However, the future will show whether the quartz-crystal microbalance will assert itself against established label-free sensor devices such as surface plasmon resonance spectroscopy and interferometry.

Piezoelectric Mass‐Sensing Devices as Biosensors—An Alternative to Optical Biosensors?

Carbon paste electrodes modified by the inclusion of either octadecylamine or stearic acid were used as solid phases to which DNA was covalently bound. Immobilized DNA was detected by voltammetry of solutions containing submillimolar quantities of Co(bpy)3(ClO4)3, Co(phen)3(ClO4)3, and Os(bpy)3-Cl2 (bpy = 2,2'-bipyridine; phen = 1,10-phenanthroline), all of which associate reversibly with immobilized DNA and yield increased peak currents at DNA-modified electrodes. Immobilization onto octadecylamine-modified electrodes was performed using a water-soluble carbodiimide, and at high DNA concentrations in the reaction mixture, it resulted in visible polymerization of DNA on the surface. Optimization of the deoxyguanosine- (dG-) selective immobilization reaction for stearic acid-modified electrodes, using water-soluble carbodiimide and N-hydroxysulfosuccinimide reagents to activate carboxylate groups on the surface, yielded conditions of 4.5% (w/w) stearic acid and 10 micrograms/mL DNA. Polythymidylic acid of 4000-base average length (poly(dT)4000) was immobilized at stearic acid-modified electrodes following enzymatic elongation with dG residues at the 3'-end. These DNA-modified electrodes were used to study hybridization with analyte poly(dA)4000 by in situ voltammetry of 60 microM Co(bpy)3(ClO4)3 at low ionic strength (20 mM NaCl), and by voltammetry of the same complex, following exposure of the electrode to poly(dA)4000 in a separate hybridization step conducted at high ionic strength (0.5 M NaCl). Results indicate slow (> or = 1 h) hybridization at low ionic strength and fast (< or = 10 min) hybridization at high ionic strength.(ABSTRACT TRUNCATED AT 250 WORDS)

Voltammetric DNA Biosensor for Cystic Fibrosis Based on a Modified Carbon Paste Electrode

Acoustic Wave Sensors

A brief overview of acoustic wave sensor physics, materials, sensor types, and applications is presented in this paper. Emphasis is placed on the different types of acoustic wave sensors, their respective advantages, and their specific applications in industry.

Acoustic wave technology sensors

A prototype biosensor, which utilizes an acoustic plate mode (APM) in a piezoelectric crystal plate as the sensing element, has been designed, fabricated and tested. The APM is selectively excited and received by aluminum interdigital transducers (IDTs), which are fabricated on a Z-cut X-propagating lithium niobate (ZX-LiNbO3) substrate using standard photolithographic techniques. The biological film is bound to the face of the ZX-LiNbO3 plate opposite to the IDTs. Appropriate r.f. electronics are used with the APM device to form the complete biosensor. Tests relating to the detection of deoxyribonucleic acid (DNA) hybridization demonstrate that the biosensor exhibits a high level of sensitivity, selectivity and reproducibility.

An acoustic plate mode biosensor

Many industrial processes have resulted in mercury contamination of soils and potentially of the surrounding groundwater. The remediation efforts for these sites requires a method of long-term verification. Sensors with lifetimes of months to years of operation without operator intervention are required to monitor these sites. One sensor geometry which is capable of detecting relevant concentrations of aqueous mercury while withstanding typical environmental conditions is the acoustic plate mode (APM) microsensor. This piezoelectric sensor protects the electronics from the potentially corrosive aqueous fluid environment while providing a significant interaction with the fluid. Gold films are employed to accumulate the mercury via surface amalgamation. The added mass is measured as a change in the resonant frequency of the piezoelectric element. A reference device helps compensate environmental factors, such as temperature drift, solution effects (viscosity, density and conductivity changes) and pressure fluctuations. Initial results indicate a sensitivity of approximately 10 ng/ml (10 μg l −1 ) which is approximately five times the limit imposed by the safe drinking water act (SDWA) in the US. Research is currently underway to lower this detection limit to allow the sensor to meet the requirements of environmental sensing, wastewater monitoring and drinking water testing.

An acoustic plate mode sensor for aqueous mercury

Acoustic wave sensors have been proposed for (bio)sensing applications for the past 20 years. One of the most attractive acoustic wave sensor geometries for these applications is the acoustic plate mode (APM) delay line. However, the use of APM delay lines has been hampered by the relative immaturity of the associated design techniques. The principle issue in the design of APM delay lines is to excite and detect electrically a single acoustic mode within the plate with distortion from intermode interference or multiple waveguide reflections. The use of single-phase unidirectional transducers (SPUDT) enables the excitation and detection of a single acoustic mode, reducing the distortions that occur in conventional transducer designs. The current work examines the sensing properties of the resulting APM device for the selective detection of chemically denatured, double-stranded deoxyribonucleic acid (ds-DNA) obtained through polymerase chain reaction (PCR) amplification of genomic viral DNA from cytomegalovirus (CMV).

Selective acoustic plate mode DNA sensor

A novel acoustic-plate-mode (APM) sensor for sensing antigen-antibody reactions has been developed. The APM sensor utilizes a Z-cut X-propagating lithium niobate (LiNbO/sub 3/) piezoelectric plate in which various types of acoustic waves are excited and received by means of a photolithographically deposited aluminum interdigital transducer (IDT). A judicious choice of the sensor operating frequency results in the selective excitation of an acoustic mode that is highly sensitive to fluid loading of the LiNbO/sub 3/ surface. This mode is then utilized as the sensing element in the sensor. Experiments have been performed using polyclonal antibodies for which the sensor has shown a strong response to the associated antigen. The biokinetics of the antigen-antibody reaction has also been studied. Experimental data compare favorably with theoretical results predicted by an affinity purified human immunoglobulin antibody-antigen model. This model immunosensor also has potentio application in directing various types of viruses such as AIDS (HIV), herpes simplex, and hepatitis. >

http://ieeexplore.ieee.org/iel2/857/2385/00067050.pdf

An acoustic plate mode immunosensor

The application of an acoustic plate mode (APM) device as an immunosensor is presented. The APM sensor utilizes a Z-cut X-propagating lithium niobate (LiNbO/sub 3/) piezoelectric plate in which various types of acoustic waves are excited and received by means of a photolithographically deposited aluminium interdigital transducer (IDT). A judicious choice of the sensor operating frequency results in the selective excitation of an acoustic mode that is highly sensitive to fluid loading of the LiNbO/sub 3/ surface. This mode is then utilized as the sensing element in the sensor. Experiments have been performed using polyclonal antibodies for which the sensor has shown a strong response to the associated antigen. The biokinetics of the antigen-antibody reaction have also been studied. Experimental data compare favorably with theoretical results predicted by an affinity-purified human immunoglobulin antibody-antigen model. This immunosensor also has potential application in detecting various types of viruses such as AIDS (HIV), herpes simplex, and hepatitis. >

D.J. McAllister

Papers

An acoustic plate mode biosensor

An acoustic plate mode sensor for aqueous mercury

Selective acoustic plate mode DNA sensor

An acoustic plate mode immunosensor

An acoustic plate mode immunosensor