Universal serial bus powered and controlled isolated constant-current physiological stimulator

Holcomb, Mark R.; Bekele, Robel Y.; Lima, Eduardo A.; Wikswo, John P.

doi:10.1063/1.3030861

Cited by 3 publications

(2 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For experimental protocols where endocardial imaging was required, the right ventricle was isolated from the rest of the rabbit heart, stretched across a Plexiglas frame, and cannulated via the right coronary artery (20). All experiments utilized either a commercial current source (Bloom), custom USB-powered and -controlled stimulators (21), or a custom high-voltage stimulator (22). Fluorescent Dye Staining.…”

Section: Methodsmentioning

confidence: 99%

The Potential of Dual Camera Systems for Multimodal Imaging of Cardiac Electrophysiology and Metabolism

Holcomb

Woods

Uzelac

et al. 2009

Exp Biol Med (Maywood)

Self Cite

View full text Add to dashboard Cite

Fluorescence imaging has become a common modality in cardiac electrodynamics. A single fluorescent parameter is typically measured. Given the growing emphasis on simultaneous imaging of more than one cardiac variable, we present an analysis of the potential of dual camera imaging, using as an example our straightforward dual camera system that allows simultaneous measurement of two dynamic quantities from the same region of the heart. The advantages of our system over others include an optional software camera calibration routine that eliminates the need for precise camera alignment. The system allows for rapid setup, dichroic image separation, dual-rate imaging, and high spatial resolution, and it is generally applicable to any two-camera measurement. This type of imaging system offers the potential for recording simultaneously not only transmembrane potential and intracellular calcium, two frequently measured quantities, but also other signals more directly related to myocardial metabolism, such as [K+]e, NADH, and reactive oxygen species, leading to the possibility of correlative multimodal cardiac imaging. We provide a compilation of dye and camera information critical to the design of dual camera systems and experiments.

show abstract

Section: Methodsmentioning

confidence: 99%

The Potential of Dual Camera Systems for Multimodal Imaging of Cardiac Electrophysiology and Metabolism

Holcomb

Woods

Uzelac

et al. 2009

Exp Biol Med (Maywood)

Self Cite

View full text Add to dashboard Cite

show abstract

“…7 Other custom stimulators have been reported that produce constant voltage and constant current for specific applications, such as Land et al, 8 Brasil et al, 9 and Cheever et al, 10 but none are suitable for our application. In our previous design, we successfully sought to overcome deficiencies in our commercial stimulators (Bloom), hereafter called legacy stimulators.…”

Section: Introductionmentioning

confidence: 96%

Continuous-waveform constant-current isolated physiological stimulator

Holcomb

Devine

Harder

et al. 2012

Review of Scientific Instruments

Self Cite

View full text Add to dashboard Cite

We have developed an isolated continuous-waveform constant-current physiological stimulator that is powered and controlled by universal serial bus (USB) interface. The stimulator is composed of a custom printed circuit board (PCB), 16-MHz MSP430F2618 microcontroller with two integrated 12-bit digital to analog converters (DAC0, DAC1), high-speed H-Bridge, voltage-controlled current source (VCCS), isolated USB communication and power circuitry, two isolated transistor-transistor logic (TTL) inputs, and a serial 16 × 2 character liquid crystal display. The stimulators are designed to produce current stimuli in the range of ±15 mA indefinitely using a 20V source and to be used in ex vivo cardiac experiments, but they are suitable for use in a wide variety of research or student experiments that require precision control of continuous waveforms or synchronization with external events. The device was designed with customization in mind and has features that allow it to be integrated into current and future experimental setups. Dual TTL inputs allow replacement by two or more traditional stimulators in common experimental configurations. The MSP430 software is written in C++ and compiled with IAR Embedded Workbench 5.20.2. A control program written in C++ runs on a Windows personal computer and has a graphical user interface that allows the user to control all aspects of the device.

show abstract

Long-pulse stability limits of the ITER baseline scenario

et al. 2015

View full text Add to dashboard Cite

DIII-D has made significant progress in developing the techniques required to operate ITER, and in understanding their impact on performance when integrated into operational scenarios at ITER-relevant parameters. Long duration plasmas, stable to m/n = 2/1 tearing modes, with an ITER-similar shape and Ip/aBT, have been demonstrated in DIII-D, that evolve to stationary conditions. The operating region most likely to reach stable conditions has normalized pressure, βN ≈ 1.9–2.1 (compared to the ITER baseline design of 1.6–1.8), and a Greenwald normalized density fraction, fGW 0.42–0.70 (the ITER design is fGW ≈ 0.8). The evolution of the current profile, using internal inductance (li) as an indicator, is found to produce a smaller fraction of stable pulses when li is increased above ≈1.1 at the beginning of βN flattop. Stable discharges with co-neutral beam injection are generally accompanied with a benign n = 2 magnetohydrodynamic mode. However if this mode exceeds ≈10 G, the onset of a m/n = 2/1 tearing mode occurs with a loss of confinement. In addition, stable operation with low applied external torque, at or below the extrapolated value expected for ITER has also been demonstrated. With electron cyclotron injection, the operating region of stable discharges has been further extended at ITER equivalent levels of torque and to edge-localized mode (ELM) free discharges at higher torque but with the addition of an n = 3 magnetic perturbation from the DIII-D internal coil set. The characterization of the ITER baseline scenario evolution for long pulse duration, extension to more ITER-relevant values of torque and electron heating, and suppression of ELMs have significantly advanced the physics basis of this scenario, although significant effort remains in the simultaneous integration of all these requirements.

show abstract

Universal serial bus powered and controlled isolated constant-current physiological stimulator

Cited by 3 publications

References 4 publications

The Potential of Dual Camera Systems for Multimodal Imaging of Cardiac Electrophysiology and Metabolism

The Potential of Dual Camera Systems for Multimodal Imaging of Cardiac Electrophysiology and Metabolism

Continuous-waveform constant-current isolated physiological stimulator

Long-pulse stability limits of the ITER baseline scenario

Contact Info

Product

Resources

About