Quartz Tuning Fork Research Articles

Calibration of the oscillation amplitude of quartz tuning fork-based force sensors with astigmatic displacement microscopy.

Quartz tuning forks and qPlus-based force sensors offer an alternative approach to silicon cantilevers for investigating tip-sample interactions in scanning probe microscopy. The high-quality factor (Q) and stiffness of these sensors prevent the tip from jumping to the contact, even at sub-nanometer amplitude. The qPlus configuration enables simultaneous scanning tunneling microscopy and atomic force microscopy, achieving spatial resolution and spectroscopy at the subatomic level. However, to enable precise measurement of tip-sample interaction forces, confidence in these measurements is contingent upon the accurate calibration of the spring constant and oscillation amplitude of the sensor. Here, we have developed a method called astigmatic displacement microscopy with picometer sensitivity.

A highly sensitive LITES sensor based on a multi-pass cell with dense spot pattern and a novel quartz tuning fork with low frequency

A highly sensitive LITES sensor based on a multi-pass cell with dense spot pattern and a novel quartz tuning fork with low frequency

Development of Multichannel Quartz Tuning Fork Sensor Array System for the Detection of Volatile Organic Compounds

Development of Multichannel Quartz Tuning Fork Sensor Array System for the Detection of Volatile Organic Compounds

Enhancement of Q factor in quartz tuning fork force sensors for atomic force microscopy through counter piezo excitation

Enhancement of Q factor in quartz tuning fork force sensors for atomic force microscopy through counter piezo excitation

Highly sensitive CO2-LITES sensor based on a self-designed low-frequency quartz tuning fork and fiber-coupled MPC

Highly sensitive CO2-LITES sensor based on a self-designed low-frequency quartz tuning fork and fiber-coupled MPC

Dual-frequency modulated heterodyne quartz-enhanced photoacoustic spectroscopy.

A novel dual-frequency modulated heterodyne quartz-enhanced photoacoustic spectroscopy (DFH-QEPAS) was demonstrated for what we believe to be the first time in this study. In traditional H-QEPAS, the frequency of modulated sinusoidal wave has a frequency difference (Δf) with the resonance frequency (f0) of a quartz tuning fork (QTF). Owing to the resonance characteristic of QTF, it cannot excite QTF to the strongest response. To achieve a stronger response, a sinusoidal wave with a frequency of f0 was added to the modulation wave to compose a dual-frequency modulation. Acetylene (C2H2) was chosen as the target gas to verify the sensor performance. The proposed DFH-QEPAS improved 4.05 times of signal-to-noise ratio (SNR) compared with the traditional H-QEPAS in the same environmental conditions.

Optical-domain modulation cancellation method for background-suppression and dual-gas detection in light-induced thermo-elastic spectroscopy

To address the issues of signal saturation and measurement range reduction caused by the background in light-induced thermoelastic spectroscopy (LITES) employing the first harmonic (1 f) modulation, an optical-domain modulation cancellation method (MOCAM) was reported in the 1f-based LITES. A balance laser source with the opposite sine modulation phase as the excitation laser source synchronously excites the quartz tuning fork (QTF) to realize background suppression. By optimizing the modulation amplitude of the balance laser and the modulation phase difference between the two laser sources, the background level was suppressed by two orders of magnitude from ∼ 7 mV to ∼ 18 μV, close to the QTF thermal noise level (∼ 1 μV). Combining the excitation laser with the balance laser enables MOCAM to overcome common mode interferences, e.g. optical path shift, laser power fluctuation, and focus position change. Furthermore, methane and water vapor (CH4/H2O) dual-gas detection based on MOCAM and time-division multiplexing method was demonstrated, and measurement range is enlarged with easy calibration due to zero background. The MOCAM-based 1f-LITES technique delivers effective background suppression and provides robustness to common mode interferences, thus establishes a feasible solution for mobile vehicle or airborne gas monitoring applications with serious environmental disturbances.

Development of continuous monitoring of ambient carbon dioxide using near-infrared quartz-enhanced photoacoustic spectroscopy

We demonstrate continuous measurement of carbon dioxide (CO2) in the atmosphere using quartz-enhanced photoacoustic spectroscopy (QEPAS) at 2.008 μm with a fiber-coupled distributed-feedback laser. The QEPAS sensor is composed of a quartz tuning fork with a resonance frequency f 0 of 12.4 kHz. The photoacoustic second-harmonic (2f) signal resulting from CO2 absorption was detected using a digital lock-in amplifier. The photoacoustic signal is proportional to the laser power. The limit of detection at an absorption line of 4980.13161 cm−1 with a line strength of 3.87 × 10−22 cm2 molecule−1 cm−1 was 12 parts per million with an integration time of 10 s. The results of the continuous monitoring of ambient CO2 using the QEPAS sensor corresponded to those obtained using a nondispersive IR sensor. The QEPAS sensor exhibited a suitable performance for field measurements of the CO2 mixing ratio.

RETRACTED ARTICLE: Demodulating an acoustic signal stimulated by photo-thermal elastic energy conversion using quartz tuning forks

RETRACTED ARTICLE: Demodulating an acoustic signal stimulated by photo-thermal elastic energy conversion using quartz tuning forks

Parallel dual tuning forks for quartz-enhanced photoacoustic spectroscopy

A recently introduced approach to photoacoustic detection of trace gases utilizing dual quartz tuning forks (D-QTFs) in parallel is described in detail. It investigates the sound vibration mode that is optimal for a small acoustic module. The acoustic module was optimized using COMSOL multiphysics software. The D-QTFs sensor and a half-size resonator module platform were adopted to enhance signal strength. The advantages of the technique compared to the normal QEPAS sensor are that it uses a single resonator tube but realises a 1.25-times signal enhancement. Water vapour was chosen as the target analyte. The achieved noise of 1σ is 1.268 µV compared to the QEPAS noise of 1.196 µV. The presence of parallel forks leads to a decrease in reaction time of ∼17 %. The results of this investigation revealed that a reduced chamber volume and rapid response led to a more pronounced signal response. The sensor's performance can be further enhanced by increasing the laser power and the optical path length. It is widely used in fields with volume constraints.

Label Free Detection of Programmed Death Ligand 1 Protein Biomarker by Quartz Tuning Fork-Based Biosensor

Programmed death-ligand 1 (PD-L1) is expressed on the membrane of many types of cancer cells such as breast and lung cancer cells. PD-L1 helps the cancerous cells to escape the surveillance of the immune system. PD-L1 also exists in a soluble form, reaching detectable levels in cancer patient’s serum. The available detection techniques for PD-L1 are time and cost demanding, requiring advance instrumentations and efforts. To overcome the challenges of the current detection techniques, functionalized quartz tuning forks are employed as biosensors for the real-time detection of PD-L1. In this study, the QTF gold coated biosensors have been functionalized by Anti PD-L1 monoclonal antibodies as a probe layer. The functionalized QTF biosensors were tested against different concentrations of PD-L1 protein ranging from 0.05 up to 500 ng ml−1, with an incubation time of 15 min. It has been observed that the QTF resonance frequency shifted correlatively with the PD-L1 concentration. Testing of other proteins has not shown significant responses indicating the suitability of the probe layer’s selectivity for PD-L1. This result is expected to open the way for a fast and early yet simple approach for the possible discovery of cancer cells in initial stages, and cancer treatment monitoring.

Matched impedance amplifier design for shear-force acoustic near-field microscopy

Efficient detection of the acoustic signal constitutes the most critical aspect in Shear-force Acoustic Near-field Microscopy, for reliably characterize the dynamic response of confined fluids under shear stress. The near-field acoustic emission from the fluid is monitored as the probe gradually approaches to, and subsequently retracts from, the substrate. Herein we report a 7dB improvement in signal-to-noise sensitivity in detecting the acoustic emission from the fluid trapped between a flat sample and the apex of a tapered probe (the latter attached to a quartz tuning fork of 32 kHz resonance frequency). The new design capitalizes on the inherent capacitance of the SANM acoustic sensor (comprising a pile of piezoelectric plates) and a proper matching inductor/capacitance combination to, altogether connected in a tank-circuit fashion, optimize the sensor’s response at 32 kHz. A detailed construction of the circuit amplifier, as well as detailed frequency response bandwidth and noise characterization, is included herein.

Miniaturized and highly-sensitive fiber-optic photoacoustic gas sensor based on an integrated tuning fork by mechanical processing with dual-prong differential measurement

A proof-of-concept gas sensor based on a miniaturized and integrated fiber-optic photoacoustic detection module was introduced and demonstrated for the purpose of developing a custom tuning-fork (TF)-enhanced photoacoustic gas sensor. Instead of piezoelectric quartz tuning fork (QTF) in conventional quartz-enhanced photoacoustic spectroscopy (QEPAS), a low-cost custom aluminum alloy TF fabricated by mechanical processing was employed as a photoacoustic transducer and the vibration of TF was measured by fiber-optic Fabry-Pérot (FP) interferometer (FPI). The mechanical processing-based TF design scheme greatly increases the flexibility of the TF design with respect to the complex and expensive manufacture process of custom QTFs, and thus it can be better exploited to detect gases with slow vibrational-translational (V-T) relaxation rates and combine with light sources with poor beam quality. The resonance frequency and the quality factor of the designed custom TF at atmospheric pressure were experimentally determined to be 7.3 kHz and 4733, respectively. Dual-prong differential measurement method was proposed to double the photoacoustic signal and suppress the external same-direction noise. After detailed optimizing and investigating for the operating parameters by measuring H2O, the feasibility of the developed sensor for gas detection was demonstrated with a H2O minimum detection limit (MDL) of 1.2 ppm, corresponding to a normalized noise equivalent absorption (NNEA) coefficient of 3.8 × 10−8 cm−1 W/Hz1/2, which are better than the QTF-based photoacoustic sensors. The proposed gas sensing approach combined the advantages of QEPAS and fiber-optic sensing, which can greatly expand the application domains of PAS-based gas sensors.

New temperature measurement method based on light-induced thermoelastic spectroscopy.

A new temperature measurement method based on light-induced thermoelastic spectroscopy (LITES) was demonstrated for the first time, to the best of our knowledge, in this manuscript. According to the thermoelastic effect of quartz tuning fork (QTF), this technique retrieves the temperature on the basis of the resonance signal of QTF. Wavelength modulation spectroscopy (WMS) combined with the dual-line method was used to achieve temperature measurement. A QTF with high-frequency selectivity and high-quality factor (Δf0 = 2.5 Hz, Q-factor = 13104.9) was used as the detection element to suppress noise and improve the signal level. Two absorption lines of water vapor (H2O) located at 7153.749 cm-1 and 7154.354 cm-1 were selected as the target line. A single distributed feedback (DFB) diode laser was used to cover the two selected absorption lines simultaneously to reduce the complexity of the sensor system. A tube furnace capable of covering a temperature range from 400°C to 1000°C was adopted to verify the performance of this method. The relative error of the measured temperature was less than 5%, which indicated that the LITES temperature sensor has excellent detection accuracy. Compared to the widely used TDLAS temperature measuring method, this LITES-based technique has the merits of low cost, has no wavelength limitation, and is expected to be applied on more occasions.

Dual-band light-induced thermoelastic spectroscopy utilizing an antiresonant hollow-core fiber-based gas absorption cell

In this paper, dual-band gas detection using a combination of the light-induced thermoelastic spectroscopy (LITES) and an antiresonant hollow-core fiber-based (ARHCF) gas absorption cell is demonstrated. The broad wavelength operation capability of a standard 32 kHz quartz tuning fork and the self-developed fiber-based gas absorption cell was exploited to demonstrate quasi-simultaneous detection of N2O and CO2, at 4570 nm (2188.2 cm−1) and 2006 nm (4985.9 cm−1), respectively. The signal analysis was based on the wavelength modulation spectroscopy technique, allowing to achieve a noise equivalent absorption coefficient (NEA) of 8.6 × 10–7 cm−1 and 1.7 × 10–6 cm−1 for N2O and CO2, respectively. The results indicate that the combination of ARHCFs with the LITES method is well suited for the design of broadband gas detectors and show remarkable potential in the fabrication of miniaturized, versatile and relatively inexpensive gas sensors operating over a wide spectral range, thus allowing multigas detection.

Effect of Gold Nanoparticle Radiosensitization on DNA Damage Using a Quartz Tuning Fork Sensor.

The development of sensor technology enables the creation of DNA-based biosensors for biomedical applications. Herein, a quartz tuning fork (QTF) sensing system was employed as a transducer for biomedical applications to address indirect DNA damage associated with gold nanoparticles (GNPs) and enhance the effectiveness of low-dose gamma radiation in radiation therapy. The experiment included two stages, namely during and after irradiation exposure; shift frequencies (Δf) were measured for 20 min in each stage. During the irradiation stage, the QTF response to DNA damage was investigated in a deionized aqueous solution with and without 100 nm GNPs at different concentrations (5, 10, 15, and 20 µg/mL). Upon exposure to gamma radiation for 20 min at a dose rate of 2.4 µGy/min, the ratio of Δf/ΔT indicates increased fork displacement frequencies with or without GNPs. Additionally, DNA damage associated with high and low GNP concentrations was evaluated using the change in the resonance frequency of the QTF. The results indicate that GNPs at 15 and 10 µg/mL were associated with high damage-enhancement ratios, while saturation occurred at 20 µg/mL. At 15 µg/mL, significant radiotherapy enhancement occurred compared to that at 10 µg/mL at 10 min after exposure. In the post-irradiation stage, the frequency considerably differed between 15 and 10 µg/mL. Finally, these results significantly depart from the experimental predictions in the post-radiation stage. They exhibited no appreciable direct effect on DNA repair owing to the absence of an environment that promotes DNA repair following irradiation. However, these findings demonstrate the potential of enhancing damage by combining GNP-mediated radiation sensitization and biosensor technology. Thus, QTF is recommended as a reliable measure of DNA damage to investigate the dose enhancement effect at various GNP concentrations.

Quartz tuning fork biosensor: A potential tool for SARS-CoV-2 detection

Portable, fast, and practical devices are important in the fight against epidemic diseases. The lack of readily available small-scale commercial solutions prompted us to delve deeper into this research effort. Investment in Quartz Tuning Fork (QTF)-based biosensor research is significant due to its seamless integration with miniaturised and portable devices. Within the scope of this study, a new, cost-effective, and versatile frequency analyser designed for detecting diseases, compatible with screens of different sizes, has been introduced. The modified QTF sensor occured mass-sensitive SARS-CoV-2 nucleocapsid protein (SARS-NP) detection with remarkable simplicity, sensitivity, and selectivity. The developed QTF-based biosensor has an impressive linear detection range ranging from 5 to 200 ng/mL and an exceptionally low limit of detection (LOD) value of 1.72 ng/mL. The sensitivity of the developed QTF-based biosensor was obtained as 50 Hz/1 μM. The biosensor response was then evaluated in commercial human serum sample. After 15 days of storage, these biosensors retained approximately 93.7 % of their initial activity. Additionally, a Scanning Electron Microscope (SEM) and Atomic Force Microscope (AFM) comprehensively characterised the electrode surface.

A novel electrochemical approach to biosensing applications: Quartz tuning forks as working electrodes for immunosensors

Although cutting-edge technology has improved our understanding of many cancers, the diagnostic and treatment options available still need to be improved. Electrochemical biosensors play a key role as the most suitable platform used for this purpose. Quartz tuning forks (QTF) sensors have recently become the most valuable components for frequency measurements, with high stability, sensitivity, and low power consumption. No paper has previously been reported on the functionalization and isolation of QTF for biomarker determination using electrochemical methods, marking this research as unique for being the first to investigate the response and sensitivity of QTFs in these applications. Cardiac troponin T (cTnT), an important biomarker of cardiovascular disease, a four-step surface modification was performed to the prepared QTFs’ prongs. The surface was investigated in detail utilizing cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods. The results showed that the QTF-based immunosensor's limit of quantitation (LOQ) was 0.81 fg/mL, and the limit of detection (LOD) was 0.24 fg/mL, with a detection range of 0.5–1500 fg/mL. The results confirmed that QTFs have unique electrode capacity in point-of-care diagnostic devices. Most importantly, due to their excellent sensitivity and low cost, QTF transducers are predicted to be widely used as a unique electrode to detect many biomarkers in EIS and CV-based electrochemical biosensors.

Sensitive Light-Induced Thermoelastic Spectroscopy-Based Oxygen Sensor With a Perovskite-Modified Quartz Tuning Fork

Sensitive Light-Induced Thermoelastic Spectroscopy-Based Oxygen Sensor With a Perovskite-Modified Quartz Tuning Fork

Detection of Aromatic Hydrocarbons in Aqueous Solutions Using Quartz Tuning Fork Sensors Modified with Calix[4]arene Methoxy Ester Self-Assembled Monolayers: Experimental and Density Functional Theory Study.

Quartz tuning forks (QTFs), which were coated with gold and with self-assembled monolayers (SAM) of a lower-rim functionalized calix[4]arene methoxy ester (CME), were used for the detection of benzene, toluene, and ethylbenzene in water samples. The QTF device was tested by measuring the respective frequency shifts obtained using small (100 µL) samples of aqueous benzene, toluene, and ethylbenzene at four different concentrations (10-12, 10-10, 10-8, and 10-6 M). The QTFs had lower limits of detection for all three aromatic hydrocarbons in the 10-14 M range, with the highest resonance frequency shifts (±5%) being shown for the corresponding 10-6 M solutions in the following order: benzene (199 Hz) > toluene (191 Hz) > ethylbenzene (149 Hz). The frequency shifts measured with the QTFs relative to that in deionized water were inversely proportional to the concentration/mass of the analytes. Insights into the effects of the alkyl groups of the aromatic hydrocarbons on the electronic interaction energies for their hypothetical 1:1 supramolecular host-guest binding with the CME sensing layer were obtained through density functional theory (DFT) calculations of the electronic interaction energies (ΔIEs) using B3LYP-D3/GenECP with a mixed basis set: LANL2DZ and 6-311++g(d,p), CAM-B3LYP/LANL2DZ, and PBE/LANL2DZ. The magnitudes of the ΔIEs were in the following order: [Au4-CME⊃[benzene] > [Au4-CME]⊃[toluene] > [Au4-CME]⊃[ethylbenzene]. The gas-phase BSSE-uncorrected ΔIE values for these complexes were higher, with values of -96.86, -87.80, and -79.33 kJ mol-1, respectively, and -86.39, -77.23, and -67.63 kJ mol-1, respectively, for the corresponding BSSE-corrected values using B3LYP-D3/GenECP with LANL2dZ and 6-311++g(d,p). The computational findings strongly support the experimental results, revealing the same trend in the ΔIEs for the proposed hypothetical binding modes between the tested analytes with the CME SAMs on the Au-QTF sensing surfaces.