TY  - JOUR
AB  - We present a nanomechanical platform for real-time quantitative label-free detection of target biomolecules in a liquid environment with mass sensitivity down to few pg. Newly fabricated arrays of up to 18 cantilevers are integrated in a micromachined fluidic chamber, connected to software-controlled fluidic pumps for automated sample injections. We discuss two functionalization approaches to independently sensitize the interface of different cantilevers. A custom piezo-stack actuator and optical readout system enable the measurement of resonance frequencies up to 2 MHz. We implement a new measurement strategy based on a phase-locked loop (PLL), built via in-house developed software. The PLL allows us to track, within the same experiment, the evolution of resonance frequency over time of up to four modes for all the cantilevers in the array. With respect to the previous measurement technique, based on standard frequency sweep, the PLL enhances the estimated detection limit of the device by a factor of 7 (down to 2 pg in 5 min integration time) and the time resolution by more than threefold (below 15 s), being on par with commercial gold-standard techniques. The detection limit and noise of the new setup are investigated via Allan deviation and standard deviation analysis, considering different resonance modes and interface chemistries. As a proof-of-concept, we show the immobilization and label-free in situ detection of live bacterial cells (E. coli), demonstrating qualitative and quantitative agreement in the mechanical response of three different resonance modes.
AU  - De Pastina, A.*
AU  - Padovani, F.
AU  - Brunetti, G.*
AU  - Rotella, C.*
AU  - Niosi, F.*
AU  - Usov, V.*
AU  - Hegner, M.*
C1  - 62257
C2  - 50752
CY  - 1305 Walt Whitman Rd, Ste 300, Melville, Ny 11747-4501 Usa
TI  - Multimodal real-time frequency tracking of cantilever arrays in liquid environment for biodetection: Comprehensive setup and performance analysis.
JO  - Rev. Sci. Instruments
VL  - 92
IS  - 6
PB  - Aip Publishing
PY  - 2021
SN  - 0034-6748
ER  - 

TY  - JOUR
AB  - Grating-based dark-field interferometry can be realized with lab-based, low-brilliance X-ray sources and provides scattering information of sample structures below the detector pixel size. This unique property allows promising medical imaging applications, especially for lung diseases. Structural damage in lung tissue caused by pulmonary emphysema or pulmonary carcinoma could be observed in radiographs by changes in the dark-field signal with high sensitivity at early stages, in contrast to the conventional absorption signal. Currently, the standard for diagnosis in the clinical routine of pulmonary diseases is absorption computed tomography (CT). The assessment of a larger number of samples with in vivo dark-field CT is limited by the rather long scan times, the order of 2 h, that are required to obtain sufficient CT data quality. In this work, a prototype in vivo, small-animal, dark-field CT is optimized with respect to CT measurements with the following: usage of an iterative reconstruction algorithm for the reduction of undersampling artifacts, a rearranged data acquisition scheme with reduced amount of dead time, and thinned gratings and curved grating geometry for more efficient utilization of the 37 kV X-ray flux. The device performance is evaluated with noise-effective dose measurements, image contrast-to-noise ratio, interferometry visibility across the field-of-view, and a reduced measurement time of 40 min with a deposited dose of 85 mGy.
AU  - Umkehrer, S.*
AU  - Birnbacher, L.*
AU  - Burkhardt, R.
AU  - Von Teuffenbach, M.*
AU  - Yildirim, A.Ö.
AU  - Pfeiffer, D.*
AU  - Herzen, J.*
AU  - Pfeiffer, F.*
C1  - 57144
C2  - 47552
CY  - 1305 Walt Whitman Rd, Ste 300, Melville, Ny 11747-4501 Usa
TI  - Optimization of in vivo murine X-ray dark-field computed tomography.
JO  - Rev. Sci. Instruments
VL  - 90
IS  - 10
PB  - Amer Inst Physics
PY  - 2019
SN  - 0034-6748
ER  - 

TY  - JOUR
AB  - An integrating measurement device for the concentration of airborne thoron decay products was designed and calibrated. It is suitable for unattended use over up to several months also in inhabited dwellings. The device consists of a hemispheric capacitor with a wire mesh as the outer electrode on ground potential and the sampling substrates as the inner electrode on +7.0 kV. Negatively charged and neutral thoron decay products are accelerated to and deposited on the sampling substrates. As sampling substrates, CR39 solid-state nuclear track detectors are used in order to record the alpha decay of the sampled decay products. Nuclide discrimination is achieved by covering the detectors with aluminum foil of different thickness, which are penetrated only by alpha particles with sufficient energy. Devices of this type were calibrated against working level monitors in a thoron experimental house. The sensitivity was measured as 9.2 tracks per Bq/m³×d of thoron decay products. The devices were used over 8 weeks in several houses built of earthen material in southern Germany, where equilibrium equivalent concentrations of 1.4–9.9 Bq/m³ of thoron decay products were measured.
AU  - Gierl, S.
AU  - Meisenberg, O.
AU  - Haninger, T.
AU  - Wielunski, M.
AU  - Tschiersch, J.
C1  - 30570
C2  - 33812
CY  - Melville
TI  - An unattended device for high-voltage sampling and passive measurement of thoron decay products.
JO  - Rev. Sci. Instruments
VL  - 85
IS  - 2
PB  - Amer Inst Physics
PY  - 2014
SN  - 0034-6748
ER  - 

TY  - JOUR
AB  - For state-of-the-art discrimination of Radon and Thoron several measurement techniques can be used, such as active sampling, electrostatic collection, delayed coincidence method, and alpha-particle-spectroscopy. However, most of the devices available are bulky and show high power consumption, rendering them unfeasible for personal exposition monitoring. Based on a Radon exposure meter previously realized at the Helmholtz Center Munich (HMGU), a new electronic prototype for Radon/Thoron monitoring is currently being developed, which features small size and weight. Operating with pin-diode detectors, the low-power passive-sampling device can be used for continuous concentration measurements, employing alpha-particle-spectroscopy and coincidence event registration to distinguish decays originating either from Radon or Thoron isotopes and their decay products. In open geometry, preliminary calibration measurements suggest that one count per hour is produced by a 11 Bq m(-3) Radon atmosphere or by a 15 Bq m(-3) Thoron atmosphere. Future efforts will concentrate on measurements in mixed Radon/Thoron atmospheres.
AU  - Irlinger, J.
AU  - Wielunski, M.
AU  - Rühm, W.
C1  - 30881
C2  - 33978
CY  - Melville
TI  - Thoron detection with an active Radon exposure meter - first results.
JO  - Rev. Sci. Instruments
VL  - 85
IS  - 2
PB  - Amer Inst Physics
PY  - 2014
SN  - 0034-6748
ER  - 

TY  - JOUR
AB  - Energy spectra of 1 keV He+ and Ar+ ion beams have been investigated using a sector field analyzer with a resolution ΔE/E<10-3. The ions were generated in a filament type plasma ion source with axial magnetic confinement. The energy spectra exhibited a unimodal, almost symmetrical peak. Width and position of the peak were measured as a function of the operating parameters of the ion source. The smallest energy spread of the ions was measured at relatively high source pressures and low magnetic field strength, in which case the full width at half-maximum of the peak was ΔE=1.5 eV. Correcting for the resolution of the analyzer, an energy spread of less than 1 eV thus appears to be achievable with the source employed in this study. Rather large peak shifts (up to 10 eV and more) were observed upon changing the axial magnetic field strength and the discharge current, the effect being much more pronounced for He than for Ar. By contrast, the peak position was almost independent of the applied discharge voltage, provided the terminal voltage was connected to the anode of the discharge. This implies that the zero point of the ion energy is closely related to the anode potential.
AU  - Glatzel, H.
AU  - Wittmaack, K.
C1  - 40603
C2  - 38750
SP  - 2765-2767
TI  - Peak position and width of the energy distribution of ion beams extracted from a plasma source.
JO  - Rev. Sci. Instruments
VL  - 63
IS  - 4
PY  - 1992
SN  - 0034-6748
ER  - 

TY  - JOUR
AB  - A setup for pulse radiolysis experiments is described consisting of the following main components: an array of 15 photomultipliers attached to a spectrograph (allowing 4032 spectra to be recorded with a time resolution of 500 ns per spectrum), self-regulating high-voltage supply for the photomultipliers, computer-controlled solution mixing and dispensing system, and provisions for continuous dose variation of the FEBETRON-accelerator electron beam. The general performance of the system is discussed and construction or electronic details are given for special components.
AU  - Saran, M.
AU  - Vetter, G.
AU  - Erben-Russ, M.
AU  - Winter, R.
AU  - Kruse, A.
AU  - Michel, C.
AU  - Bors, W.
C1  - 41167
C2  - 40121
SP  - 363-368
TI  - Pulse radiolysis equipment: A setup for simultaneous multiwavelength kinetic spectroscopy.
JO  - Rev. Sci. Instruments
VL  - 58
IS  - 3
PY  - 1987
SN  - 0034-6748
ER  - 

TY  - JOUR
AB  - Transient digitizers based on RCA flash converters are used to record two-parameter data for chromosome analysis.
AU  - Weier -, H.U.G.
AU  - Eisert, W.G.
C1  - 42481
C2  - 36256
SP  - 2902
TI  - Two-parameter data-acquisition system for slit-scan chromosome analysis.
JO  - Rev. Sci. Instruments
VL  - 57
IS  - 11
PY  - 1986
SN  - 0034-6748
ER  - 

TY  - JOUR
AB  - A simple particle analyzer has been developed using a modified high speed flow through technique and absorption measurements of a continuous He Ne laser beam. From pulse shape analysis and the integration of absorption pulses, size distributions of stained or unstained cells can be derived. The range of 5-300 μ is covered without changing the flow system and a rate up to 200,000/sec can be achieved. Typical applications in cell analyses are shown.
AU  - Eisert, W.G.
AU  - Ostertag, R.
AU  - Niemann, E.G.
C1  - 42252
C2  - 38433
SP  - 1021-1024
TI  - Simple flow microphotometer for rapid cell population analysis.
JO  - Rev. Sci. Instruments
VL  - 46
IS  - 8
PY  - 1975
SN  - 0034-6748
ER  - 

TY  - JOUR
AB  - The design and working principle of a flash x ray system are described. A two stage Marx generator is used, the charging voltage is 150 kV and the stored energy 1125 J. Anode and cathode are arranged coaxially. The anode consists of a tungsten coated aluminium tube of 20 mm i.d. into which the substances to be irradiated are placed. Measurements of electrical and radiation parameters are described. The x ray dose per pulse is 400 rad, the half width of the pulse is 0.2 μsec and the mean quantum energy is 44 keV. An example for the application of the system in microsecond pulse radiolysis is presented.
AU  - Hinsch, H.
AU  - Scheel, H.E.
AU  - Niemann, E.G.
C1  - 41633
C2  - 35508
SP  - 650-652
TI  - A 400 rad flash x ray system for pulse radiolysis.
JO  - Rev. Sci. Instruments
VL  - 45
IS  - 5
PY  - 1974
SN  - 0034-6748
ER  -