Single chip dynamic nuclear polarization microsystem

The integration on a single chip of the sensitivity-relevant electronics of nuclear magnetic resonance (NMR) and electron spin resonance (ESR) spectrometers is a promising approach to improve the limit of detection, especially for samples in the nanoliter and subnanoliter range. Here we demonstrate the co-integration on a single silicon chip of the front-end electronics of an NMR and an ESR detector. The excitation/detection planar spiral microcoils of the NMR and ESR detectors are concentric and interrogate the same sample volume. This combination of sensors allows to perform dynamic nuclear polarization (DNP) experiments using a single-chip integrated microsystem having an area of about 2 mm$^2$. In particular, we report $^1$H DNP-enhanced NMR experiments on liquid samples having a volume of about 1 nL performed at 10.7 GHz(ESR)/16 MHz(NMR). NMR enhancements as large as 50 are achieved on TEMPOL/H$_{2}$O solutions at room temperature. The use of state-of-the-art submicrometer integrated circuit technologies should allow the future extension of the single-chip DNP microsystem approach proposed here up the THz(ESR)/GHz(NMR) region, corresponding the strongest static magnetic fields currently available. Particularly interesting is the possibility to create arrays of such sensors for parallel DNP-enhanced NMR spectroscopy of nanoliter and subnanoliter samples

UHF Radio Frequency Modules for Satellite-Ground Communication

This thesis is devoted to the development of a bidirectional telecommunication system for space applications. The module is going to be integrated in the AraMiS architecture, that is an innovative philosophy of small satellites based on tile-modularity and the use of low-cost commercial components. The objective is to design the electronic board, the antenna apparatus and the control software to handle both the communication protocol and the housekeeping functions. According to the AraMiS speci cations, the main constraints are collected in Table I. After an introduction referring to space-environment related issues and the state of the art in university satellites, the hardware design is carried out. Technical choices related to frequency selection, modulation and suitable equipment are taken and justi ed according to the power budget, project constraints and the availability of speci c products on market. A set of devices is analyzed in terms of key-parameters in order to lter the most appropriate ones for each goal, then main block-schematics are provided. By means of speci c CAD tools, both schematics and PCB implementation are performed and depicted in the following chapters, then the C++ control software is designed to drive the communication system, the processing unit and all the housekeeping sensors. Since only COTS components are going to be used due to the low-cost goal and those are neither space dedicated nor radiation robust, both protection circuits and speci c software routines must be implemented in order to keep electronic boards in safe operating region. Such a precaution is fundamental to prevent the mission failure in case of SEUs. After that, the propagation environment is studied and the most common UHF radiating systems for satellite-ground communications are described. Finally, a suitable AraMiS antenna and speci c microwave circuits are designed to ensure both impedance matching and high radiation e ciency in the band of interest. In order to assure the system compatibility within the AraMiS framework and full technical integration with the other subsystems, a UML description for the entire project documentation is developed and steadily updated in the project library

High sensitivity field asymmetric ion mobility spectrometer

A high sensitivity field asymmetric ion mobility spectrometer (FAIMS) was designed, fabricated, and tested. The main components of the system are a 10.6 eV UV photoionization source, an ion filter driven by a high voltage/high frequency n-MOS inverter circuit, and a low noise ion detector. The ion filter electronics are capable to generate square waveforms with peak-to-peak voltages up to 1000 V at frequencies up to 1 MHz with adjustable duty cycles. The ion detector current amplifier has a gain up to 1012 V/A with an effective equivalent input noise level down to about 1 fA/Hz1/2 during operation with the ion filter at the maximum voltage and frequency. The FAIMS system was characterized by detecting different standard chemical compounds. Additionally, we investigated the use of a synchronous modulation/demodulation technique to improve the signal-to-noise ratio in FAIMS measurements. In particular, we implemented the modulation of the compensation voltage with the synchronous demodulation of the ion current. The analysis of the measurements at low concentration levels led to an extrapolated limit of detection for acetone of 10 ppt with an averaging time of 1 s

Single-chip electron spin resonance detectors operating at 50 GHz, 92 GHz, and 146 GHz

We report on the design and characterization of single-chip electron spin resonance (ESR) detectors operating at 50 GHz, 92 GHz, and 146 GHz. The core of the single-chip ESR detectors is an integrated LC-oscillator, formed by a single turn aluminum planar coil, a metal-oxide-metal capacitor, and two metal-oxide semiconductor field effect transistors used as negative resistance network. On the same chip, a second, nominally identical, LC-oscillator together with a mixer and an output buffer are also integrated. Thanks to the slightly asymmetric capacitance of the mixer inputs, a signal at a few hundreds of MHz is obtained at the output of the mixer. The mixer is used for frequency down-conversion, with the aim to obtain an output signal at a frequency easily manageable off-chip. The coil diameters are 120 μm, 70 μm, and 45 μm for the U-band, W-band, and the D-band oscillators, respectively. The experimental frequency noises at 100 kHz offset from the carrier are 90 Hz/Hz1/2, 300 Hz/Hz1/2, and 700 Hz/Hz1/2 at 300 K, respectively. The ESR spectra are obtained by measuring the frequency variations of the single-chip oscillators as a function of the applied magnetic field. The experimental spin sensitivities, as measured with a sample of α,γ-bisdiphenylene-β-phenylallyl (BDPA)/benzene complex, are 1 × 108 spins/Hz1/2, 4 × 107 spins/Hz1/2, 2 × 107 spins/Hz1/2 at 300 K, respectively. We also show the possibility to perform experiments up to 360 GHz by means of the higher harmonics in the microwave field produced by the integrated single-chip LC-oscillators