Analytical platforms based on impedance spectroscopy are promising for non‐invasive and label‐free analysis of single cells as well as of their extracellular matrix, being essential to understand cell function in the presence of certain diseases. Here, an innovative rolled‐up impedimetric microfulidic sensor, called sensor‐in‐a‐tube, is introduced for the simultaneous analysis of single human monocytes CD14+ and their extracellular medium upon liposaccharides (LPS)‐mediated activation. In particular, rolled‐up platinum microelectrodes are integrated within for the static and dynamic (in‐flow) detection of cells and their surrounding medium (containing expressed cytokines) over an excitation frequency range from 102 to 5 × 106 Hz. The correspondence between cell activation stages and the electrical properties of the cell surrounding medium have been detected by electrical impedance spectroscopy in dynamic mode without employing electrode surface functionalization or labeling. The designed sensor‐in‐a‐tube platform is shown as a sensitive and reliable tool for precise single cell analysis toward immune‐deficient diseases diagnosis.
In this paper, a high-performance water-coupled ultrasonic ranging technique is presented. We improved the conventional time-of-flight (ToF) ranging technique based on digital correlation of pseudo random noise (PRN) waveforms by introducing signal carrier phase shift detection with an I/Q coherent reception method. In this way, the spatial resolution is dominated mainly by the digitization resolution of the analog to digital converter (ADC) used in the receiver circuit. Submicrometer resolution is achieved in the entire full-scale-range (FSR) while keeping the ADC sampling rate at the Nyquist sampling limit at the carrier ranging signal frequency. In this study, we use quadrature amplitude modulation (QAM) waveforms of a set of 1023-bit GPS Gold codes with 8 MHz carrier as a ranging signal. Experiments carried out in a water vessel reveal micrometer level accuracy and precision for quasi-static and dynamic cases. It is experimentally illustrated that the proposed method is capable of multiplexing. The optimal ranging performance is approached by selecting an appropriate set of systemic technical parameters and ranging signals. This allows to define the figure of merit (FOM) indicating the performance upper bound of such a ranging system.
Colossal magnetoresistance is of great fundamental and
technological
significance in condensed-matter physics, magnetic memory, and sensing
technologies. However, its relatively narrow working temperature window
is still a severe obstacle for potential applications due to the nature
of the material-inherent phase transition. Here, we realized hierarchical
La0.7Sr0.3MnO3 thin films with well-defined
(001) and (221) crystallographic orientations by combining substrate
modification with conventional thin-film deposition. Microscopic investigations
into its magnetic transition through electron holography reveal that
the hierarchical microstructure significantly broadens the temperature
range of the ferromagnetic–paramagnetic transition, which further
widens the response temperature range of the macroscopic colossal
magnetoresistance under the scheme of the double-exchange mechanism.
Therefore, this work puts forward a method to alter the magnetic transition
and thus to extend the magnetoresistance working window by nanoengineering,
which might be a promising approach also for other phase-transition-related
effects in functional oxides.
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