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High-speed velocimetry in microfluidic protein mixers using confocal fluorescence decay microscopy
摘要： A method to measure fluid speeds on the order of 10,000 mm/s in microchannels is presented. A microfluidic protein mixer is manufactured with a 170 μm microscope coverslip bottom that interfaces with a confocal florescence microscope using a water-immersed Olympus UPLSAPO 60XW objective to create a diffraction-limited confocal volume. A diode laser with a repetition rate of 1 MHz is used to study Poiseuille flows at average speeds of 5000, 6000 and 7000 mm/s by exciting tris(2,2′-bipyridine)ruthenium(II) hexafluorophosphate solution at 1 μmol/L concentration flowing through the micro-mixer in the confocal volume. Decays collected using a time-correlated single photon counting card at each grid point are characterized by the first moment of the decay and curve fitted with the theoretical Poiseuille flow solutions. It was found that curve fitting with higher average speeds results in lower errors. A fluorescence correlation study was then carried out at different depths in the micro-mixer to understand the raw data profiles observed using the diode laser. A mixing study was then carried out using a Ti-Sapphire laser with a repetition rate of 3.8 MHz. A Poiseuille flow at 7000 mm/s was measured using the Ti-Sapphire laser and then curve fitted to the theoretical Poiseuille flow solution. The curve fit was then applied to the complicated flow region to determine speed. Results of the experimental mixing study are also compared to direct numerical simulation results.
关键词： Microfluidic protein mixers,High-speed velocimetry,Poiseuille flows,Fluorescence correlation spectroscopy,Confocal fluorescence decay microscopy
更新于2025-09-09 09:28:46
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A Low Power Receiver Front-End Design With Tunable Notch Filter for TX Leakage and Blocker Suppression
摘要： An active transmitter self-leakage suppressor for frequency-division duplex transceivers is presented. A wideband active notch ?lter is implemented at the mixer IF ports to suppress out the transmitter leakage. Since the active notch ?lter is operating at IF frequencies, its noise, power, and area consumption penalty for the overall transceiver is negligible, and it does not require any complicated amplitude and phase calibration circuitry that is necessary for the cancelers which operate at RF frequencies. Due to the transfer function seen by the active notch-?lter, its noise and distortion contribution is shaped and reduced further. The proposed design is implemented in a 65 nm standard CMOS process for an LTE receiver and provides minimum of 5 dB attenuation at duplex distance for E-UTRA band 20. For the same frequency band, it enhances the IIP2 and IIP3 of the receiver with a minimum of 12 and 6 dB, respectively. The active ?lter consumes only 1.1 mA/channel from a 2.5 V supply and occupies 0.078 mm2/channel. Its noise contribution is within the NF measurement error, thus negligible. The design is intended and tested for transmitter self-interference and wideband ACS blockers.
关键词： wideband notch ?lter,FDD transceivers,low duplex distances,wide signal bandwidth,SAW-less,voltage commutating mixers,LTE receivers,active self-leakage canceler,transmitter self-leakage
更新于2025-09-09 09:28:46
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[IEEE 2018 15th European Radar Conference (EuRAD) - Madrid, Spain (2018.9.26-2018.9.28)] 2018 15th European Radar Conference (EuRAD) - A Highly Integrated Dual Band FMCW Radar Receiver for Indoor Positioning Applications
摘要： This work presents the design of a highly integrated dual band frequency modulated continuous wave (FMCW) radar receiver (RX) at the 2.4 and 5.8 GHz industrial, scientific and medical bands. As opposed to earlier versions of this work, baseband low pass filtering is performed by the integrated variable gain amplifier (VGA) thus eliminating the need for an off-chip low pass filter (LPF) together with the required chip pads needed for this external filter. Fabricated on an IBM 0.18 μm BiCMOS process as part of a dual band FMCW radar transceiver (TRX), the measured RX performance is in good agreement with simulations and measurements from previous RX versions with the external LPF achieving a dynamic range of more than 50 dB and a baseband signal-to-noise ratio (SNR) of around 18 dB at -70 dBm radio frequency (RF) input power and an input-referred 3rd order intercept point (IIP3) of around -7 dBm. To the best of the author’s knowledge, with a chip area of 2.4 mm2, this filterless dual band FMCW radar TRX has the highest level of integration reported in the literature.
关键词： radar,receivers,Amplifiers,gain control,mixers,filters,phase locked loops
更新于2025-09-04 15:30:14