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Real-time multianalyte biosensors based on interference-free multichannel monolithic quartz crystal microbalance
(2015-05-05)
Jaruwongrungsee, Kata
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Waiwijit, Uraiwan
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Wisitsoraat, Anurat
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Sangworasil, Manas
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Pintavirooj, Chuchart
In this work, we design, fabricate and characterize a new interference-free multichannel monolithic quartz crystal microbalance (MQCM) platform for bio-sensing applications. Firstly, interference due to thickness-shear vibration mode coupling between channels in MQCM array is effectively suppressed by interposing a polydimethylsiloxane wall between adjacent QCM electrodes on a quartz substrate to form inverted-mesa-like structure. In addition, the electrical coupling due to the electrical impedance of solution is diminished by extending the flow path between them with an extended-design flow channel. The electrical testing results show that individual QCM signal is unaffected by those of adjacent channels under liquid loading, signifying the achievement of interference-free MQCM. The MQCM is applied for multi-analyte biosensing of IgG and HSA. The anti-IgG and anti-HSA are separately immobilized on two adjacent QCM electrodes, which are subsequently blocked with BSA to avoid unspecific binding. The MQCM biosensors are tested with single- and double-analyte solutions under continuous flow of buffer. The IgG and HSA QCM sensors only show frequency shift responses to their corresponding analytes and there are very small cross frequency shifts due to remnant unspecific binding. Moreover, MQCM sensors show approximately linear frequency shift response with analyte concentration. Therefore, the developed MQCM platform is promising for real-time interference-free label-free detection and quantification of multiple bio-analytes.
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Metamaterial-based microfluidic sensor for dielectric characterization
(2013-01-01)
Withayachumnankul, Withawat
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Jaruwongrungsee, Kata
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Tuantranont, Adisorn
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Fumeaux, Christophe
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Abbott, Derek
A microfluidic sensor is implemented from a single split-ring resonator (SRR), a fundamental building block of electromagnetic metamaterials. At resonance, an SRR establishes an intense electric field confined within a deeply subwavelength region. Liquid flowing in a micro-channel laid on this region can alter the local field distribution and hence affect the SRR resonance behavior. Specifically, the resonance frequency and bandwidth are influenced by the complex dielectric permittivity of the liquid sample. The empirical relation between the sensor resonance and the sample permittivity can be established, and from this relation, the complex permittivity of liquid samples can be estimated. The technique is capable of sensing liquid flowing in the channel with a cross-sectional area as small as (0.001λ<inf>0</inf>)<sup>2</sup>, where λ<inf>0</inf> denotes the free-space wavelength of the wave excitation. This work motivates the use of SRR-based microfluidic sensors for identification, classification, and characterization of chemical and biochemical analytes. © 2012 Elsevier B.V.
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Metamaterial-inspired microfluidic-based sensor for chemical discrimination
(2012-12-01)
Jaruwongrungsee, Kata
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Withayachumnankul, Withawat
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Wisitsoraat, Anurat
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Abbott, Derek
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Fumeaux, Christophe
This work proposes a metamaterial-inspired microfluidic-based chemical sensor. The sensor comprises a microwave split-ring resonator (SRR), an important building block of metamaterials, integrated with a disposable flow-channel made of a transparency film. The electromagnetic response of the sensor is observed in the presence of various analytes including glycerol, ethanol, and phosphate buffered saline. It is found that the resonance frequency in the transmission amplitude and the zero crossing in the reflection phase of the sensor are good features for discrimination of these analytes and for determining their concentrations. The developed metamaterial-inspired microfluidic-based chemical sensor has a potential for advanced chemical sensing applications. © 2012 IEEE.
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Metamaterial-inspired multichannel thin-film sensor
(2012-04-24)
Withayachumnankul, Withawat
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Jaruwongrungsee, Kata
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Fumeaux, Christophe
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Abbott, Derek
A multichannel thin-film sensor is implemented from a set of microstrip-coupled split-ring resonators (SRRs) with different dimensions. Each SRR exhibits a unique high-Q resonance that is sensitive to the presence of a sample in a particular area. Hence, this SRR-based sensor can function (i) to detect different samples simultaneously to increase the throughput or (ii) to characterise nominally identical samples at multiple frequencies to increase the sensor selectivity. In addition, the sensitivity of this SRR-based sensor is optimized through strategic design of the resonator shape to produce a strong confined electric field at each sensing region. The design principle is validated with simulation and measurement. Owing to the optimized design, sensing a low-permittivity film with a thickness as small as one thousandth of the operating wavelength is achievable. © 2012 IEEE.
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High-sensitivity humidity sensor utilizing PEDOT/PSS printed quartz crystal microbalance
(2011-08-12)
Jaruwongrungsee, Kata
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Sriprachuabwong, Chakrit
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Sappat, Assawapong
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Wisitsoraat, Anurat
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Phasukkit, Pattarapong
In this work, quartz crystal microbalance humidity sensor was fabricated by inkjet printing technique. Poly (3, 4-ethylenedioxythiophene)/poly-styrene- sulfonic acid (PEDOT/PSS), one of the most widely used polymer composites, was printed on QCM electrode as sensing layer using Dimatrix material inkjet printer. The main advantage of this coating method is its high precision of solution coating with accurately controlled volume and area. The printed layer was varied from 1 to 20 layers. With 20 PEDOT/PSS printed layers, the humidity sensitivity is found increased by more than three orders of magnitude compared to uncoated QCM. In addition, the PEDOT/PSS coated QCM exhibits fast humidity detection with short response and recovery times. Thus, the PEDOT/PSS printed on the QCM electrode is an effective way to improve humidity-sensing characteristic of QCM. © 2011 IEEE.
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Design and simulation of flow cell chamber for quartz crystal microbalance sensor array
(2010-07-30)
Jaruwongrungsee, Kata
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Maturos, Thitima
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Sritongkum, Pornpimol
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Wisitsora-At, Anurat
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Pintavirooj, Chuchart
In this paper, the cause of significant variation in sensing responses of identical QCM sensors array in a circular QCM chamber is analyzed by fluid dynamic simulation. Moreover, the simulation is used to determine an appropriate shape of flow chamber for QCM sensor array. Simulation results show that the flow in a circular-shaped QCM chamber design is primarily turbulent. In addition, the degree of turbulence is increased with flow rate. Thus, sensors at various locations see different sample dispersions causing their sensing behaviors to be significantly different. The QCM chamber has been redesigned to be rectangular line and simulation results indicate that it can be the solution to the problem because flow in the new design is primarily laminar with uniform sample velocity.
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Symmetrical poly MUMPs-based piezoresistive microcantilever sensors with on-chip temperature compensation for microfluidics applications
(2008-05-01)
Tuantranont, Adisorn
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Lomas, Tanom
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Jaruwongrungsee, Kata
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Jomphoak, Apichai
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Wisitsoraat, Anurat
Microelectromechanical systems (MEMS)-based cantilever beam sensors for microfluidics applications with on-chip temperature sensors for temperature drift compensation were developed. The stress induced on gold surface with polysilicon piezoresistive sensing is demonstrated. In principle, adsorption of biochemical species on a functionalized surface of the microfabricated cantilever will cause surface stress and, consequently, cantilever bending. The sensing mechanism relies on the piezoresistive properties of the doped polysilicon wire encapsulated in the beam. The beam is constructed through multiusers MEMS Process (PolyMUMPs) foundry with postprocessing silicon etching. Bending analysis is performed so that the beam tip deflection can be predicted. The piezoresistor designs on the beams were varied, within certain constraints, so that the sensitivity of the sensing technique could be measured by external read-out circuit. The mass detection of 0.0058-0.0110 g is measured by the beam resistor series as a balanced Wheatstone bridge configuration. The voltage output of the bridge is directly proportional to the amount of bending in the MEMS cantilever. The temperature dependency and sensor performance have been characterized in experiments. Compensation by resisters on the substrate significantly reduces the temperature dependence. © 2008 IEEE.

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