A5056219418- Photonic and Optical Devices
- Neuroscience and Neural Engineering
- Photonic Crystals and Applications
- Photoreceptor and optogenetics research
- Neural dynamics and brain function
- Advanced Data Compression Techniques
- Plasmonic and Surface Plasmon Research
- Energy Harvesting in Wireless Networks
- Advanced Fiber Optic Sensors
- Optical Network Technologies
- Speech and Audio Processing
- Advanced Memory and Neural Computing
- EEG and Brain-Computer Interfaces
- Optical Coatings and Gratings
- Phase-change materials and chalcogenides
- Advanced Battery Technologies Research
- Metamaterials and Metasurfaces Applications
- Advanced Antenna and Metasurface Technologies
- Ocular and Laser Science Research
- Neurological disorders and treatments
- Underwater Vehicles and Communication Systems
- Visual perception and processing mechanisms
- Underwater Acoustics Research
- Green IT and Sustainability
- Advanced Fiber Laser Technologies
MIT Lincoln Laboratory
2019-2024
Draper Laboratory
2017-2020
VA Boston Healthcare System
2010-2012
Massachusetts General Hospital
2010-2011
Harvard University
2010-2011
Boston University
2003-2010
Providence VA Medical Center
2010
Australian National University
2000-2008
Centre for Ultrahigh Bandwidth Devices for Optical Systems
2004-2007
The University of Sydney
2006
Electrical stimulation is currently used to treat a wide range of cardiovascular, sensory and neurological diseases. Despite its success, there are significant limitations application, including incompatibility with magnetic resonance imaging, limited control electric fields decreased performance associated tissue inflammation. Magnetic overcomes these but existing devices (that is, transcranial stimulation) large, reducing their translation chronic applications. In addition, not effective...
Electric stimulation of the CNS is being evaluated as a treatment modality for variety neurological, psychiatric, and sensory disorders. Despite considerable success in some applications, existing techniques offer little control over which cell types or neuronal substructures are activated by stimulation. The ability to more precisely activation would likely improve clinical outcomes associated with these applications. Here, we show that specific frequencies sinusoidal can be used...
Antennas that operate in the very low frequency (LF) band and below are useful for a number of applications, including long-distance underwater communication. When constrained size, antennas electrically small inefficient. This has motivated need novel approaches to LF antenna design. Here, we present concepts generate electromagnetic signals from mechanical motion. We first review generated fields efficiency conventional magnetic electric dipole transmitters. is then extended their...
fMRI investigation on the neural substrates involved in tactile imagery is reported. Healthy subjects performed mental of stimulation dorsal aspect right hand. The results were compared with regions activation during actual stimulation. During imagery, contralateral primary and secondary somatosensory areas activated along left parietal lobe. Activations inferior frontal gyri (Brodmann's area 44), dorsolateral prefrontal area, precentral gyrus, insula, medial gyrus also observed. In basal...
A description is given of the voice activity detector (VAD) standardized by CEPT for use in Pan-European digital cellular mobile telephone service. The speech-coding algorithm chosen a 13-kb/s speech coder, using technique which produced at decoder passing substitute residual through long-term and short-term predictor filters. difficulties detecting noisy environment are discussed, performance tests carried out to validate design described. show that clipping levels very low but recorded...
Retinal prostheses aim to restore functional vision those blinded by outer retinal diseases using electric stimulation of surviving neurons. Previous work indicates that repetitive with stimuli activate the synaptic network reduces sensitivity neurons further stimulation. Such desensitization may contribute fading visual percepts over time reported human subjects. Here, we show be more complex than previously considered. We recorded spike trains from rabbit ganglion cells and found persists...
Wireless neural stimulators are being developed to address problems associated with traditional lead-based implants. However, designing wireless on the sub-millimeter scale (<1mm3) is challenging. As device size shrinks, it becomes difficult deliver sufficient power operate device. Here, we present a sub-millimeter, inductively powered stimulator consisting only of coil receive power, capacitor tune resonant frequency receiver, and diode rectify radio-frequency signal produce excitation. By...
Abstract Implementation of gene editing technologies such as CRISPR/Cas9 in the manufacture novel cell-based therapeutics has potential to enable highly-targeted, stable, and persistent genome modifications without use viral vectors. Electroporation emerged a preferred method for delivering gene-editing machinery target cells, but major challenge remaining is that most commercial electroporation machines are built research process development rather than large-scale, automated cellular...
Antennas that operate in the low-frequency (LF) band and below are useful for a number of applications. However, long wavelengths result very low efficiency antennas could be made portable. This has motivated need novel approaches electrically short antenna design. Here, we present concept an electromagnetic transmitter operates by mechanically moving bound static charge. The resulting motion induces fields similar to dipole antenna. voltage, current, resistance conventional replaced force,...
Grayscale lithography is a widely known but underutilized microfabrication technique for creating three-dimensional (3-D) microstructures in photoresist. One of the hurdles its widespread use that developing grayscale photolithography masks can be time-consuming and costly since it often requires an iterative process, especially complex geometries. We discuss PROLITH, simulation tool, to predict 3-D photoresist profiles from mask designs. Several examples optical microsystems...
Wireless power delivery to implantable devices has been traditionally achieved through low-frequency (<;10 MHz) inductive coupling. More recent work moved toward the UHF band (300 MHz-3 GHz), with models showing maximal efficiency is at these frequencies. However, for many applications, maximizing a secondary goal received implant, and it remains unclear whether optimal frequency different than power. Furthermore, previous generally do not include ferrite core in which could shift frequency....
We experimentally and computationally demonstrate high transmission through arrays of coaxial apertures with different geometries arrangements in silver films. By studying both periodic random apertures, we were able to isolate enhancement phenomena owing surface plasmon effects from those the excitation cylindrical plasmons within themselves.
The output of retinal ganglion cells depends on local and global aspects the visual scene. receptive field is well studied classically consists a linear excitatory center antagonistic surround. contains pools nonlinear subunits that are distributed widely across retina. subunit mediate in uncertain ways various behaviors cells, like temporal-frequency doubling, saccadic suppression, contrast adaptation. To clarify mechanisms function, we systematically examined effect remote grating patterns...
Extracellular electric stimulation with sinusoidal waveforms has been shown to allow preferential activation of individual types retinal neurons by varying stimulus frequency. It is important understand the mechanisms underlying this frequency dependence as a step toward improving methods activation. In order elucidate these mechanisms, we implemented morphologically realistic model bipolar cell and measured response extracellular waveforms. We compared passive membrane kinetics...
We are investigating the use of novel stimulus waveforms in neural prostheses to determine whether they can provide more precise control over temporal and spatial pattern elicited activity as compared conventional pulsatile stimulation. To study this, we measured response retinal ganglion cells both sinusoidal white noise waveforms. The cell-attached whole cell patch clamp recordings allowed responses be observed without significant obstruction from artifact. Electric stimulation with...
We report Bragg grating structures fabricated by focused ion beam milling in optical waveguides, and demonstrate that they can be used as a powerful diagnostic of modes very high index waveguides. show higher-order lossy modes, which present large numbers even single-moded silicon-on-insulator dramatically affect the transmission spectra gratings these though are normally not observable. Our results only illuminate challenges to realize practical but raise possibility devices based on mode...
Recent developments in peripheral nerve electrodes allow the efficient and selective neuromodulation of somatic autonomic nerves, which has proven beneficial specific bioelectronic medical applications. However, current most clinical devices are wired powered by implantable batteries suffer from several limitations. We recently developed a sub-millimeter inductively neural stimulator (electroparticle; EP), this study, we report integration EP onto commercial cuff (EP-C) allowing wireless...
Abstract Action potentials were recorded from rat retinal ganglion cell fibers in the presence of a uniform field, and maintained discharge pattern was characterized. Spike trains under ketamine–xylazine anesthesia generally stationary, while those urethane often showed slow, undriven, quasiperiodic fluctuations firing rate. In light these nonstationarities, interspike interval distributions power spectral densities are reported for data collected primarily ketamine–xylazine. The majority...
Electrocardiogram (ECG) monitoring is a critical tool in patient care, but its utility often balanced with frustration from clinicians who are constantly distracted by false alarms. This has motivated the need to readdress major factors that contribute ECG noise goal of reducing In this study, we describe previously unreported phenomenon which can result an unintended interaction between two systems: 1) dc lead-off circuitry used detect whether electrodes fall off patient; and 2) right-leg...
The DTX (discontinuous transmission) system that has been standardized by CEPT for the pan-European digital mobile radio is described. In this mode transmitter switched on when a user begins to talk and off again he or she stops. There are two reasons using DTX: increase number of channels (by 100% more) which can be accommodated in given bandwidth reduce power drain hand portable equipment. It noted that, while adding little degradation speech channel very additional cost, will considerably...
The miniaturization of optical devices and their integration for creating adaptive reconfigurable photonic integrated circuits requires effective platforms methods to control light over very short distances. We present here several techniques objects that we have developed harness at the sub-micrometer scale. These new tools include planar crystal on nonlinear chalcogenide glasses, tapered silica fibres, optofluidics, trapping. Their association could provide basic building blocks completely...