A Portable Chip-Based NMR Relaxometry System With Arbitrary Phase Control for Point-of-Care Blood Analysis

IEEE Transactions on Biomedical Circuits and Systems, vol. 17, pp. 831–842

Abstract

In this article, we present a portable NMR relaxometry system optimized for the point-of-care analysis of body liquids such as blood. The presented system is centered on an NMR-on-a-chip transceiver ASIC, a reference frequency generator with arbitrary phase control, and a custom-designed miniaturized NMR magnet with a field strength of 0.29 T and a total weight of 330 g. The NMR-ASIC co-integrates a low-IF receiver, a power amplifier, and a PLL-based frequency synthesizer on a total chip area of 1100$\boldsymbol{\times }$900$\mu$m$\boldsymbol{^{2}}$. The arbitrary reference frequency generator enables the use of conventional CPMG and inversion sequences, as well as modified water-suppression sequences. Moreover, it is used to implement an automatic frequency lock to correct temperature-induced magnetic field drifts. Proof-of-concept measurements on NMR phantoms and human blood samples show an excellent concentration sensitivity ofv$\boldsymbol{_\text{c,min}}$= 2.2 mM/$\boldsymbol{\sqrt{\text{Hz}}}$. This very good performance renders the presented system an ideal candidate for the future NMR-based point-of-care detection of biomarkers such as the blood glucose concentration.

Authors 6

1. Frederik Dreyer

   University of Stuttgart

   Affiliation as printed

   Institute of Smart Sensors, University of Stuttgart, Stuttgart, Germany

2. Qing Yang

   University of Stuttgart

   Affiliation as printed

   Institute of Smart Sensors, University of Stuttgart, Stuttgart, Germany

3. Belal M.K. Alnajjar

   University of Stuttgart

   Affiliation as printed

   Institute of Smart Sensors, University of Stuttgart, Stuttgart, Germany

4. Daniel Krüger

   Harvard University · University of Stuttgart

   Affiliation as printed

   Institute of Smart Sensors, University of Stuttgart, Stuttgart, Germany

   John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA

5. Bernhard Blümich Aachen Institute of Technical and Macromolecular Chemistry

   RWTH Aachen University

   Affiliation as printed

   Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Aachen, Germany

6. Jens Anders

   University of Stuttgart · Institut für Mikroelektronik Stuttgart · Center for Integrated Quantum Science and Technology

   Affiliation as printed

   Institute of Smart Sensors, University of Stuttgart, Stuttgart, Germany

   Center for Integrated Quantum Science and Technology, Stuttgart, Germany

   Institute for Microelectronics Stuttgart, IMS CHIPS, Stuttgart, Germany