High-resolution micro-magnetometer based on novel nano-junction oxide SQUIDs

This Phase II project will develop a general purpose magnetic microscope and evaluate its utility in biomedical sciencesThe microscope will detect the magnetic field using high transition temperaturehigh Tcsensors based on the superconducting quantum interference deviceSQUIDdeveloped during the Phase IUC RiversideUCRhas developed a novel high Tc SQUID fabrication technique that gives a junction noise comparable to that of low Tc SQUIDsTheir approach uses a focused helium ion beam to make the Josephson junction withnm precisionresulting in reliablereproducible SQUIDs with high yieldsDuring Phase I we have designed three magnetometers based on this SQUIDWe found the direct injection magnetometer to produce a junction noise ofoHz comparable with a low Tc SQUID noiseWe mounted the best one just below the window of a microscope stage in an inverted microscope and determined its field sensitivity atoK to bepTHz for an effective detector area ofm radiusIn AimUCR will improve the noise level further by optimizing the dimensions of the junctionthe SQUID loop and the coupling efficiency with the pickup loopUCR will constructxSQUID chips and deliver them to Tristan in yearTristanmeanwhilewill design and construct an inverted SQUID microscopeiSMbased on their previous iSMIt will be equipped with an up right fluorescent microscope above and micromanipulators for stimulator and recording electrodes on the sidesThe window in the microscope stage will have a micro channel etched inside to achieve a distance ofm between a sample and the SQUID array for single nanoparticle and neuron detectionThis very short gap is possible because the SQUIDs are high Tc superconductors and thus they operate at andgtoKThey will mount two of the test SQUID chips into axarray and evaluate their sensitivitiesOnce a working iSM is constructedit will be shipped to Boston for evaluating its utility in biomedical sciences by the beginning of yearAfter shipping the iSMUCR will continue to improve their SQUID chipsOnce they achieve a significant reduction in detector noiseBoston will ship the iSM back to Tristan and Tristan will test the iSM with the improved SQUID chipsTristan will ship back the improved iSM to Boston for continuing the evaluationIn AimDrOkada of Moment and DrLin of Boston UniversityBUwill use an isolated crayfish giant axon during yearto develop the method for magnetic field detection from single neuronsDrMan of BU will develop cultured hippocampal neurons from fetal ratsIn yearDrsOkada and Lin will evaluate the iSM for measuring intracellular currents from single neuronsIn AimDrOkada and DrMedarova of the Martinos Center at Massachusetts General Hospital will construct nanoparticles and fluorescent dye conjugated with avidin and biotinThey will magnetize the nanoparticles using an AC method and test whether the iSM can detect single complexesThis will serve as the proof of concept for future applicationsThe fluorescent signals from the same complex will be measured with the optical microscope for comparative studiesPhase II deliverablesthe iSMa performance reportpublications In the Phase II of this projectwe will use the best high critical temperaturehigh TcSQUIDsuperconducting quantum interference devicemagnetic field detector developed during the Phase I to develop an inverted SQUID microscopeiSMequipped with the magnetic field detector just below the microscope stagean up right fluorescent microscope above and stimulating and recording electrodes from the sidesWe will test whether this iSM is capable detecting single nanoparticles and single neuronsTo the extent that we can develop an iSM with this level of sensitivitywe will be able to develop a new type of iSMs for commercialization that is useful in biomedical and neurosciences