Month: December 2018

How Stimulator Hardware and Software Work Together

In order to create an effective stimulation experiment, two main components are necessary – the stimulator software and and stimulator hardware module. Let’s briefly examine how they work together.

The Stimulator setup window in AcqKnowledge Software is an onscreen toolbox used for constructing  the stimulus waveform type, shape, duration, repetition, and displays a graphical representation of the stimulus type being presented. It also controls how often the stimulus starts and stops within the software. These controls extend to cleverly being able to output two different stimulus types simultaneously, such as a pulse in one channel and a tone in the other. It is bascially the canvas upon which the stimulation paradigm is created, and provides a blueprint for the output.

But without the stimulator hardware, these sophisticated setups are merely waveforms on a screen. In order to control the intensity or voltage level of the stimulation signal and output it to a participant, it’s necessary to incorporate simulator hardware, such as the STM100C stimulator module.

The STM100C, which connects directly to the BIOPAC MP160 System, has a number of controls for outputting and interacting with the stimulation signal generated by the software, the main one of which is the level control on the front panel. This enables you to increase or decrease the amplitude or intensity on the software stimulation waveform, and whereas the waveform shape will remain unaltered, the power of the pulse can be attenuated as desired. The STM100C can also interface with headphones (for audio stimulus), LEDs, and other devices. The STM100C module itself is not powerful enough to generate much voltage on its own, so to provide the desired voltage or current range for nerve conduction studies, an isolation adapter is required. Think of these adapters as small amplifiers that multiply the STM100C voltage or current output to the proper levels needed for the study. Isolation adapters plug directly into the STM100C unit, and the electrodes connected to the participant interface to the isolation adapters. Additionally, a monitoring cable can also be connected so the voltage or current output can be viewed onscreen in AcqKnowledge.

We also invite you to view a free webinar on various stimulation techniques using BIOPAC hardware and software.

BIOPAC offers a wide array of wired and wireless equipment that can be used in your research. To find more information on solutions for recording and analyzing signals such as ECG, heart rate, respiration and more using any platforms mentioned in this blog post, you can visit the individual application pages on the BIOPAC website.

Understanding Stimulation Hardware

Physiology studies often involve the recording of responses from subjects who are reacting to a particular sensory input being presented, otherwise known as stimulation. The presented stimuli can take several forms, and are tightly controlled in lab environments for the comfort and safety of the subject. Different types of human and animal stimulation consist of:

  • Electrical
  • Haptic (touch)
  • Thermal (temperature)
  • Olfactory (scent)
  • Auditory (sound)
  • Visual (light, such as a strobe)

The following is an introduction to some stimulation hardware commonly used in the research market:

Stimulator Modules such as the BIOPAC STM100C is one of the building blocks for many types of stimulation protocols and create a variety of pulse and waveform outputs for nerve conduction, evoked response, audio stimulus-response, and somatosensory response studies. The STM100C interfaces with the BIOPAC MP150 or MP160 data acquisition system and a wide range of devices such as headphones, LEDs, piezo transducer for audio alarms, or haptic transducers. The device also provides technician control of the stimulus level, and works in concert with the AcqKnowledge software Stimulation setup window.

Stimulus Isolation Adapters: These adapters are added to the STM100C module and multiply the output of the STM100C by 5 or 10x to provide the desired range for nerve conduction, muscle twitch, or other studies requiring a stronger stimulus than what the STM100C can generate on its own.

The STM200 is a standalone device that interfaces with the Analog Outputs on the front panel of the Universal Interface (UIM100C) or High Level Transducer Interface (HLT100C) modules. This is a very powerful stimulator, capable of outputting up to 1 amp. It can be used for human and animal applications, including isolated tissue bath preparations.

Linear Isolated Stimulator: The STMISOLA Linear Isolated Stimulator is the most advanced and powerful stimulator offered by BIOPAC. This type of unit can handle almost any application and far exceeds most typical hardware devices in terms of flexibility and control. Typically, stimulators can only generate simple unipolar or bipolar pulses. The STMISOLA, however, can output unipolar or bipolar arbitrary waves such as pulse (single or train), square, sine, triangle, exponentially decaying, modulated envelopes, and fully user-specified types. STMISOLA can be used for Transcranial Direct Current Stimulation (tDCS) and High Definition Transcranial Direct Current Stimulation (HD-tDCS. These are forms of electrical stimulation to effect neuro-modulation in the brain.

Stroboscope: The TSD122 Stroboscope resembles a handheld flashlight and is used for visual evoked response applications and for synchronizing triggers. The unit has a range from zero to a maximum of 12,000 flashes per minute.

Haptic Stimulator: The TSD190 Haptic Stimulator incorporates an internal electromagnetically actuated plunger which can be used to mechanically stimulate a 1.5 mm diameter area of skin surface; both plunger force and travel can be infinitely adjusted between zero and a specified maximum value. This type of stimulator connects directly to the STM100C Stimulator Module and is used for tactile or somatosensory studies.

Thermal Stimulator: The STMTHERM* Thermal Stimulator is used for applying 5-second hot or cold temperature pulses to a  4 cm x 4 cm skin area. AcqKnowledge software controls the actual output from the MP160 data acquisition unit and the stimulator hardware multiplies the signal to achieve the desired voltage or current levels.

Auditory Stimulator: The OUT101 Tubephone is used to deliver aural stimulus in the form of clicks or tones for auditory evoked responses studies such as auditory brainstem response (ABR) and resembles a tube, which is worn in the ear. It connects directly to the STM100C Stimulator Module.

We hope the above thumbnail sketch serves as an introduction to various stimulator hardware and common stimulation protocols. Please visit the above linked content for more in-depth information.

We also invite you to view our free webinar, Stimulation Techniques for Researchers, available on-demand.

*STMTHERM Thermal Stimulator will be available soon! Stay tuned.

BIOPAC offers a wide array of wired and wireless equipment that can be used in your research. To find more information on solutions for recording and analyzing signals such as ECG, heart rate, respiration and more using any platforms mentioned in this blog post, you can visit the individual application pages on the BIOPAC website.

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