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Hf2li

Manufactured by Zurich Instruments
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Sourced in Switzerland

The HF2LI is a high-performance lock-in amplifier from Zurich Instruments. It is designed for precise measurements of signals in the frequency range up to 50 MHz. The HF2LI provides advanced signal processing capabilities, including demodulation and filtering, to enable accurate and reliable measurements of complex waveforms.

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Lab products found in correlation

Labview, by National Instruments (3 mentions) Fds1010, by Thorlabs (3 mentions) Hf2ta, by Zurich Instruments (2 mentions) Poly l lysine (pll), by Zurich Instruments (2 mentions) Fv1200mpe, by Olympus (2 mentions) Xlplan n, by Olympus (2 mentions) Sr560, by Stanford Research Systems (1 mentions) Cm 3000, by Leica (1 mentions) Insight deepsee, by Spectra-Physics (1 mentions) Uplsapo60xw, by Olympus (1 mentions) Cypher s, by Oxford Instruments (1 mentions) Spm 9600, by Shimadzu (1 mentions) Omcl ac240tn, by Olympus (1 mentions) Apd410c, by Thorlabs (1 mentions) Msa 500, by Polytec (1 mentions) Matlab, by MathWorks (1 mentions) High o d shortpass filter, by Thorlabs (1 mentions) Diy multiphoton, by Olympus (1 mentions) Fv3000 software module fv osr, by Olympus (1 mentions) Ppp efm, by Nanosensors (1 mentions)

Close spelling variants of this product

HF2LI lock-in amplifier (16 citations) HF2Li PLL (5 citations)

33 protocols using hf2li

1

Ionic Liquid-Gated FET Sensing Protocol

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Time-series measurements were performed following the schematic in Figure 2a. The signal on the ionic liquid-gate (VLG) was switched between an arbitrary function generator (HF2LI; Zurich Instruments, Zurich, Switzerland) or a pH microelectrode (MI-4156; Microelectrodes, Bedford, NH). An offset voltage, Vo (GS200; Yokogawa Corporation, Tokyo, Japan), was then added to VLG using a summing amplifier (SR560; Stanford Research Systems Inc., Sunnyvale, CA). The FET was operated in a constant current mode using a PID controller that varied VBG in response to changes in ID. The channel current was first amplified using a current preamplifier (DLPCA-200; FEMTO, Berlin, Germany) with a transimpedance gain of 106 V/A. The amplified voltage was input to a digital PID controller (HF2LI; Zurich Instruments, Zurich, Switzerland), filtered using a 4-pole Bessel low pass filter (LPF) with a bandwidth of 5 kHz and then sampled at 25 kHz using a 14-bit analog to digital converter. The PID controller varied VBG in response to changes in ID with a bandwidth of 1 kHz (KP=496.1, KI=9.242×103 s−1 and KD=8.02 μs). The PID output was used to drive the back-gate voltage (VBG) between −10 V to +10V.
Le S.T., Guros N.B., Bruce R.C., Cardone A., Amin N.D., Zhang S., Klauda J.B., Pant H.C., Richter C.A, & Balijepalli A. (2019). Quantum Capacitance-Limited MoS2 Biosensors Enable Remote Label-Free Enzyme Measurements. Nanoscale, 11(33), 15622-15632.
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2

Precise Electrochemical Measurements with PID Control

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Time-series measurements were performed by operating the nFETs and dg2DFETs under proportional-integral-derivative (PID) control (HF2LI; Zurich Instruments, Zurich, Switzerland). The channel current, ID, was maintained at a constant value by continuously varying the back-gate voltage (VBG) in the case of the dg2DFETs or by adding the controller output to the signal from the pH sensor (VpH) for the nFETs in response to changes in the top-gate potential.
The PID control system was implemented by first amplifying the channel current, ID, with a current preamplifier (DLPCA-200; FEMTO, Berlin, Germany) at a gain of either 106 V/A (dg2DFET) or 103 V/A (nFET). The output of the current preamplifier was then filtered through a 4-pole Bessel filter with a cutoff frequency of 5 kHz and sampled with a frequency of 25 kHz by using a 14-bit analog-to-digital converter (HF2LI; Zurich Instruments, Zurich, Switzerland). The digital PID controller (KP=553.5 mV, KI=9.22×103 s−1 and KD=10.4 μs) was operated with a bandwidth of 1 kHz to maintain the channel current set-point. Because most biological processes are slow and do not require high bandwidth measurements, the controller output was further filtered by using a low-pass filter with a cutoff frequency of 10 Hz prior to being recorded.
Le S.T., Morris M.A., Cardone A., Guros N.B., Klauda J.B., Sperling B.A., Richter C.A., Pant H.C, & Balijepalli A. (2020). Rapid, Quantitative Therapeutic Screening for Alzheimer’s Enzymes Enabled by Optimal Signal Transduction with Transistors. The Analyst, 145(8), 2925-2936.
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3

Infrared Nano-Imaging Using s-SNOM

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The infrared nano-imaging measurement in this work is accomplished using a home-built scattering-type scanning near-field optical microscope (s-SNOM). To perform infrared nano-imaging, the metallic tip (Nanoandmore HQ:NSC15/Cr-Au-100, tip apex radius ~20 nm) of a tapping mode AFM (Bruker Innova) is illuminated from the side with a p-polarized infrared beam (Access laser L3S CO2 laser, wavelength ~10.6 µm). At the excitation wavelength of 10.6 µm, the plasmonic responses of both SWNT and graphene are prominent and the effects from the phonon bands of h-BN and SiO2 substrates are negligible. The metallic tip is tapped at a frequency of Ω ~240 kHz, with an amplitude of ~80 nm. The signal backscattered from the tip apex carries local optical information of the sample and is captured by an MCT detector (Kolmar Technologies KLD-0.1-J1/11/DC) in the far field. To suppress the background scattering from the tip shaft and sample, the detector signal is demodulated at a frequency of 3 Ω by a lock-in amplifier (Zurich Instruments HF2LI). By recording the demodulated signal while scanning the sample, near-field images are obtained simultaneously with the topography.
Wang S., Yoo S., Zhao S., Zhao W., Kahn S., Cui D., Wu F., Jiang L., Utama M.I., Li H., Li S., Zibrov A., Regan E., Wang D., Zhang Z., Watanabe K., Taniguchi T., Zhou C, & Wang F. (2021). Gate-tunable plasmons in mixed-dimensional van der Waals heterostructures. Nature Communications, 12, 5039.
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4

Ultrafast Optical Spectroscopy Using Tunable Pulses

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A tunable titanium-sapphire oscillator system (Coherent, Chameleon Ultra II, 80 MHz) was used to directly generate infrared push pulses (1100 nm) and to pump an optical parametric oscillator (Coherent, OPO Compact) to generate visible pump pulses (450 nm). The pump beam frequency of 2 kHz was selected using a commercial acousto-optic pulse picker (PulseSelect pulse picker from STFC), and the push line frequency was given by a homemade acousto-optic pulse selector at 1 kHz. Reference photocurrent from a photodiode was detected at the pump repetition frequency by a lock-in amplifier (Zurich Instruments HF2LI). The push beam’s effect on the photocurrent was detected by the lock-in amplifier. A ∼0.5 nJ pump and a ∼0.1 μJ push pulse were focused into a ∼0.2 mm2 spot on the device with an objective lens.
Armstrong C.L., Price M.B., Muñoz-Rojas D., Davis N.J., Abdi-Jalebi M., Friend R.H., Greenham N.C., MacManus-Driscoll J.L., Böhm M.L, & Musselman K.P. (2015). Influence of an Inorganic Interlayer on Exciton Separation in Hybrid Solar Cells. ACS Nano, 9(12), 11863-11871.
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5

High-Speed Hyperspectral SRS Imaging of Liver Tissue

Cited 2 times
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Liver tissue was fixed in 10% formalin and then embedded in Tissue-Tek optimal cutting temperature compound. Frozen liver tissues sectioned to 30 μm thick using Cryostat (Leica CM 3000) were subjected to hsSRS imaging analysis as previously described (53 (link), 62 (link), 63 (link)). Briefly, the spectral focusing–based hsSRS system was used, with a dual-output femtosecond laser (InSight DeepSee; Spectra-Physics) providing pump (800 nm) and Stokes (1040 nm) pulses at an 80 MHz repetition rate. An electro-optical modulator (EO-AM-R-C2; Thorlabs) was used to modulate the Stokes laser at a resonant frequency of 10.5 MHz. The time delay line controlled by a motorized stage was employed, and the microscope (BX51; Olympus) equipped with a water objective (UPLSAPO 60XW; Olympus) was used for laser scanning and imaging. The pump beam was detected by a photodiode (S3994-01; Hamamatsu) with two installed short-pass filters (ET980SP; Chroma), and the SRS signals were acquired by a lock-in amplifier (HF2 LI; Zurich Instruments). The laser power of pump and Stokes beams were set to 50 and 70 mW (measured before galvanometer), respectively.
Li Y., Huang S., Wang J., Dai J., Cai J., Yan S., Huang Z., He S., Wang P., Liu J, & Liu Y. (2022). Phosphorylation at Ser724 of the ER stress sensor IRE1α governs its activation state and limits ER stress–induced hepatosteatosis. The Journal of Biological Chemistry, 298(6), 101997.
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6

Frequency-Modulated Atomic Force Microscopy

Cited 1 time
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Atomic force microscopy (AFM)
images were acquired with a Cypher S from Oxford Instruments under
a dry air atmosphere and ambient conditions. To improve the electrostatic
sensitivity, Pt-coated AC240 cantilevers from an Olympus were used.
The scans were performed using frequency-modulated AFM with a net-attractive
feedback (frequency shift of ca. −15 Hz, amplitude of ca. 18
nm) at a scan speed of 2.5 μm per second. The topography images
were leveled and flattened using Gwyddion.109 (link) Simultaneously, we determined the local surface potential of the
sample by using FM-KFM with sideband demodulation. A home-built algorithm
based on a Kalman filter was used to improve the feedback performance.77 (link) Both AFM and KFM controls were performed on
an external device (HF2LI) from Zurich Instruments. Further details
of the KFM setup may be found elsewhere.77 (link),78 (link)
Lu B., Vegso K., Micky S., Ritz C., Bodik M., Fedoryshyn Y.M., Siffalovic P, & Stemmer A. (2023). Tunable Subnanometer Gaps in Self-Assembled Monolayer Gold Nanoparticle Superlattices Enabling Strong Plasmonic Field Confinement. ACS Nano, 17(13), 12774-12787.
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7

Electrical Packaging and Characterization of MEMS Resonators

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The die embedding the vacuum-sealed MEMS resonators is electrically packaged in a ceramic leadless chip carrier. The device is operated in an ambient room temperature environment. The bias voltages are generated by a low noise voltage source (Keysight B2961A). The drive and pump signals are provided by a two-channel lock-in amplifier (Zurich Instruments HF2LI). The response motion of the resonator is detected by a capacitance–voltage converting scheme that is based on charge amplifier, and measured by the lock-in amplifier. The simulation codes are based on Python 3.7 with NumPy and Matplotlib packages.
Zhou X., Zhao C., Xiao D., Sun J., Sobreviela G., Gerrard D.D., Chen Y., Flader I., Kenny T.W., Wu X, & Seshia A.A. (2019). Dynamic modulation of modal coupling in microelectromechanical gyroscopic ring resonators. Nature Communications, 10, 4980.
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8

Transepithelial Electrical Resistance Measurement

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TEER was measured using a lock-in amplifier (HF2LI, Zurich Instruments, Switzerland) operated by a customized LabVIEW program. Before each measurement, the medium inside the chip was refreshed to reach room temperature to minimize measurement errors caused by the changes in temperature and medium conductivity. In the microfluidic chip, two electrodes were located above and below the PC membrane, respectively. The impedance values between any two electrodes were recorded with an AC signal of ∼0.8 V applied to one terminal and the other terminal grounded. The response current was amplified by a current amplifier (HF2TA, Zurich Instruments, Switzerland) with an amplification of 108. Afterward, the amplified signals were fed to the HF2LI for demodulation, with the oscillator frequency set to 10 kHz and the signal sampling rate set to 7K Sa/s. Based on the equivalent resistive circuit and the Gaussian elimination, the TEER value was calculated using Eq. 1, discussed in Section 3.1.
Li Y., Xu M., Zhu Z., Xu F, & Chen B. (2023). Transendothelial electrical resistance measurement by a microfluidic device for functional study of endothelial barriers in inflammatory bowel disease. Frontiers in Bioengineering and Biotechnology, 11, 1236610.
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9

Frequency Shift Imaging with FM-AFM

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We used lab-modified FM-AFM instruments based on a Shimadzu SPM-9600 with a home-build controller programmed in LabVIEW (National Instruments). A silicon cantilever (OMCL-AC240TN, Olympus), whose nominal second spring constant and resonance frequency in the imaging solution were 91 N/m and 150 kHz, respectively, was used. The cantilever was oscillated at its second resonance frequency and the frequency shift was detected by a digital phase-locked loop (HF2LI, Zurich Instruments). The typical oscillation amplitude was 0.5 nm peak-to-zero. WSxM (Nanotech Electronica)34 (link) was used to analyze the obtained data.
Kominami H., Kobayashi K, & Yamada H. (2019). Molecular-scale visualization and surface charge density measurement of Z-DNA in aqueous solution. Scientific Reports, 9, 6851.
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10

Optical Trapping Particle Dynamics

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To perform phase- or frequency-locking experiments, the particle motion is tracked by an avalanche photodiode (APD; Thorlabs, APD410C), which measures the forward-scattered light from the trapped particle. The APD signal is processed by a lock-in amplifier (Zurich Instruments, HF2LI, 210 MSa/s, DC-50 MHz) to extract the oscillation frequency and its phase of the particle oscillation. A frequency-doubled waveform with an adjusted phase shift relative to the particle oscillation is superimposed to the voltage waveform driving an acousto-optic modulator (IntraAction, DTD-274HD6M) to modulate the trap intensity (±5%). The PSD is taken over continuous 17.2 hours for phase locking (Fig. 5B) and 30 hours for frequency locking (Fig. 5C).
Arita Y., Simpson S.H., Zemánek P, & Dholakia K. (2020). Coherent oscillations of a levitated birefringent microsphere in vacuum driven by nonconservative rotation-translation coupling. Science Advances, 6(23), eaaz9858.
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