Integration of the sensitivity-relevant electronics of nuclear magnetic resonance (NMR) and electron spin resonance (ESR) spectrometers on a single chip is a promising approach to improve the limit of detection, especially for samples in the nanoliter and sub-nanoliter range. As a group, we are designing integrated sensors for NMR and ESR spectroscopy using different integrated technologies such as CMOS, HEMT and SiGe.
10 GHz Single Chip DNP Microsystem
We have recently demonstrated the cointegration on a single silicon chip of the front-end electronics of NMR and ESR detectors. 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 one to perform dynamic nuclear polarization (DNP) experiments using a single-chip integrated microsystem having an area of about 2 mm2. NMR enhancements as large as 50 are achieved on TEMPOL/H2O solutions at room temperature. The chip is fabricated using a standard silicon CMOS technology (TSMC 180 nm, MS/RF).
An Ultra-Low Power 35 GHz Electron Spin Resonance Detector
A low power microwave oscillator designed as sensor for electron spin resonance (ESR) spectroscopy. Low power consumption is necessary for low temperature operation. Additionally, lower power consumption allows for a lower microwave magnetic field in the sensing volume, which avoids the saturation of samples having long spin relaxation times and, consequently, the degradation of the spin sensitivity. The oscillator operates at 35 GHz, consuming 90 µW at 300 K and 15 µW at 1.4 K. This is the lowest power consumption reported to date for oscillators operating in the same frequency range. The fully integrated oscillator is based on a single HEMT transistor having a gate length of 70 nm and realized using a 2DEG in In0:7Ga0:3As. The detector operates at down to 1.4 K.
Keywords: NMR, ESR, DNP, spectroscopy
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