The Eyes Have It—Mobile Eye Tracking

Eye tracking has been a consistent player in the physiological research field for a number of years, and more recently a “mobile” variation of this technology has become increasingly widespread. But just what is mobile eye tracking and how does it work? Unlike eye tracking studies tethered to a lab, where a participant visually follows an object on a computer screen, mobile eye tracking data can be acquired outside of the lab. All that is required, in fact, is a pair of glasses. Not just any glasses, but ETVision glasses, capable of recording not only multiple parameters of a participant’s “eye image” but also the scene the participant is gazing at and responding to. Let’s look briefly on how eye tracking glasses work. The lightweight ETVision glasses are equipped with two eye-facing cameras combined with a pair of LEDs for recording the various components of the “eye image,” such as pupil size/position, gaze path, fixation (when the participant’s eyes lock onto an area of interest), internal and external data markers, vergence angle (angle between the eyes), and corneal reflections (CRs). The cameras also look at the contrast between the pupil and the surrounding iris. This constant real-time feedback is recorded every 5.5 milliseconds and the eye images are rendered at 180 frames per second.

In addition to eye cameras, a built-in forward-facing 720p scene camera records the viewable area in front of the participant. This enables the landscape or scenery the participant is looking at to be combined and synchronized with the eye image data (say, if the participant is driving a car or riding a mountain bike).

Did I say riding a mountain bike? Yes. Full eye tracking data can be collected and stored in a 256 GB SD card and the logged data exported to a .*csv file, which in turn can be imported into AcqKnowledge software along with other logged physiological data. The glasses also have a coated visor for reducing glare. (Glare causes squinting and the eye tracking cameras do not perform as well on eyes that are squinting or closing due to excessive light or reflections.)

In addition, a small microphone built into the eyeglasses enables two-way audio between the investigator and the participant. Already wear glasses? No problem. Eye tracking glasses can be worn over corrective lenses without issue. However, contact lenses should be cleaned before wearing them under eye tracking glasses. The glasses are connected to a small controller via a standard HDMI cable, and the controller houses a 256 GB SD card. In addition to the SD card used for logging remote data, the controller can also be connected to a host computer via WiFi or LAN. The lithium-polymer battery will run the eye tracking glasses for 5.5 hours on a full charge.

Using the AcqKnowledge software’s Media feature, the eye tracking video data can be replayed with a tight correlation to other physiological data collected during the experiment by the BioNomadix Logger. (Other data acquisition hardware types, such as MP160 or MP36R, can be used within the lab.) The eye tracking video and graph data can be displayed side-by-side on the screen. Placing the I-beam cursor at any point in the AcqKnowledge graph takes you to the corresponding point in the eye-tracking video (say, during activities such as driving a car). Eye tracking data for vertical position, horizontal position, pupil diameter, and more can be imported as channels into the AcqKnowledge graph. This data will be synchronized with the eye tracking video, along with any added event markers.

Interested in more details about ETVision Eye Tracking Glasses and AcqKnowledge software? To see it all in action, we invite you to view our free on-demand Mobile Eye Tracking Webinar.

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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Top Signals for Life Science Instruction

Experience has shown that beginning physiology students are more engaged when acquiring and viewing signals from their own (or a lab partner’s) bodies in real time, particularly signals that are noninvasive to capture and easy to acquire. Watching a waveform trace across the screen and respond immediately to physical input is a sure-fire way to spark wonder and curiosity in a student. The following is a list (in no particular order) of the most common signals gathered in a beginning lab environment using the Biopac Student Lab System.

Electromyogram (EMG)

EMG is probably the top signal as far as simplicity, as the EMG signal can be consciously and directly controlled by the student, whether it be by simply making a fist to contract the forearm muscle or squeezing a hand dynamometer to measure grip strength. In addition to a raw EMG signal, a second channel showing integrated EMG can be simultaneously displayed. (Biopac Student Lab Lesson 1 and Lesson 2.)

Electroencephalogram (EEG)

EEG is another easy-to-acquire signal. Although not consciously controllable as EMG, the student can observe differences in the four simple periodic rhythms present in brain activity (alpha = 8-13 Hz, beta = 13-30 Hz, delta = 1-5 Hz, and theta = 4-8 Hz) while engaged in activities such as opening/closing eyes, solving simple mental math problems, or hyperventilating. (Biopac Student Lab Lesson 3 and Lesson 4.)

Electrocardiogram (ECG)

The ECG represents electrical events of the cardiac cycle whereas Ventricular Systole and Ventricular Diastole represent mechanical events (contraction and relaxation of cardiac muscle, passive opening and closing of intracardiac valves, etc.). Because the ECG reflects electrical activity, it is a useful “picture” of heart activity and presents several interesting components under various conditions, such as while sitting, standing, lying down, and after deep breathing or exercise. Various lead configurations highlight observable differences in the QRS complex which become apparent in analysis. (Biopac Student Lab Lessons 5, 6, and 7.)

Respiration (RSP) cycle and pulmonary function

As easy as breathing, measuring RSP signals under a variety of circumstances is another common study. Using a respiratory transducer (SS5LB) and an airflow transducer (SS11LB), we can record and analyze chest expansion and contraction during the breathing cycle, as well as pulmonary volumes/capacities and the effects of aerobic exercise. (Biopac Student Lab Lessons 8, 12, 13, and 15.)

Electrooculogram (EOG)

Large and small movements of the eye can be tracked and studied under various conditions by attaching simple adhesive electrodes to the forehead and temples in conjunction with the same SS2L electrode lead set used for recording EMG and ECG signals. (Biopac Student Lab Lesson 10.)

Reaction Time

Possibly the most fun signal to record. The participant holds a hand switch (SS10L) and pushes the button when an aural (click sound) or visual (light flash) stimulus is presented. The reaction time interval between the presentation of the stimulus and the participant’s voluntary reaction (button push) are recorded and analyzed. A variety of stimuli are presented, such as reaction to a fixed stimulus (e.g., every four seconds) opposed to a random stimulus (one to 10 seconds). Reactions are recorded holding the hand switch alternately in both the right and the left hand. It’s interesting to compare the difference in reaction time elicited from the dominant vs. non-dominant hand in response to the aural or visual stimulus. (BSL Lessons 11 and 11A.)

Other signals and studies commonly acquired in Biopac Student Lab are:

We also invite you to watch a free on-demand webinar detailing Biopac Student Lab Lessons.

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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Meet Them Where They Are—Portable Wireless Solutions

Once relegated to tightly controlled lab environments where electrode-laden participants were observed at close quarters, researchers are now able to extend the lab into the everyday environment over nearly limitless distances. Top quality physiological data can be acquired from untethered subjects performing tasks ranging from sleeping comfortably in their own beds to engaging in high-impact sports. How and when did this deep dive into unfettered physiology become possible? We offer a brief examination of the solutions currently offered as the 2020s emerge.

BioNomadix BioShirt

Lightweight, comfortable, and some might even say fashionable, the BioNomadix BioShirt uses a respiration sensor and fabric electrodes to wirelessly record respiration and ECG from ambulatory subjects performing unfettered tasks in short or long-term studies, in the lab, or in the real world. The shirt connects to a BioNomadix wireless Respiration & ECG Transmitter (BN-RSPEC) secured in a small pocket on the front of the BioShirt—no electrodes, gels, or wires need apply. Wireless data can be transmitted to a BioNomadix Smart Center, Logger or matched Receiver+MP160/MP150 System. BioShirts provide a high level of comfort and are ideal for long-term physiological monitoring. The ECG and respiratory signal are obtained by means of sensors made of yarns that are fully integrated into the shirt’s textile structure. Sensors are made of fibers directly woven during the production process, and connections between sensors are obtained using conductive fibers for a totally unobtrusive, highly comfortable sensorized garment. The base yarn is composed of anallergic and antibacterial materials to guarantee safe and prolonged use. Machine washable with mild detergent—do NOT use fabric softener.

Smart Center

The BioNomadix Smart Center is a small-form USB-powered data acquisition unit that can record data from up to three wireless BioNomadix transmitters at a time. The transmitters are automatically detected and paired using a guided setup wizard. Smart Center is compatible with 14 different BioNomadix Transmitter types encompassing all major body signals. AcqKnowledge data acquisition and data analysis software also supports monitoring transmitter battery levels, automatic configuration of derived signals and guided analysis based on the type of recorded signals. Adhesive Velcro disks are included for mounting on various surfaces. Smart Center offers a compact and sophisticated physiology platform that sets up in minutes. Simply plug the Smart Center into the computer, set up the transmitters and subject, then start recording high quality data with AcqKnowledge software.

BioNomadix Wireless Wearable Physiology Logger

Offering the industry’s only system that delivers a comprehensive, 24-hour data logging solution in an easy-to-use, easy-to-wear package, the BioNomadix Logger truly delivers “physiology anywhere.” The BioNomadix Logger is the perfect tool for applications that demand greater degrees of subject freedom and complex experimental design. BioNomadix Loggers wirelessly record physiological data as subjects freely and naturally live their lives.

BioHarness Telemetry and Logging Systems

BioHarness with AcqKnowledge software is a lightweight portable biological data logger and telemetry system that monitors, analyzes, and records a variety of physiological parameters including ECG, respiration, posture, and acceleration. BioHarness applications include physiology, psychology, psychophysiology, exercise physiology, ergonomics, human factors, and more. The BioHarness operates in Bluetooth transmitting mode for live viewing of data or data logging mode. In the data logging mode, BioHarness acquires and saves the data for later download to AcqKnowledge software using the included USB docking and charging cradle.

Eye Tracking Glasses ETV

The ETVision (ETV) wearable unit resembles a pair of eyeglasses that can be worn by itself or over the participant’s prescription eyeglasses. The glasses incorporate miniature “eye cameras” for viewing each eye and a “scene camera” that views what the participant is looking at. A built-in microphone is included, and an optional visor can be mounted to the front of the headgear. Recording video and audio data to an SD card for later data processing allows the participant to be completely untethered during data recording. This is useful while engaging in long term activities away from the lab such as walking, bicycling, or driving.

For more information about BIOPAC wireless solutions, we invite you to view the following resources:

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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Eye Tracking Basics

eye tracking basics
Eye Tracking Basics | Eye Structure

To understand how eye tracking works, it is important to have a basic knowledge of the structure of the eye.

  • pupil—an aperture, or opening, in the iris that allows light to enter into the eye unless viewed exactly on-axis with a light source, the pupil appears black
  • iris—the colored part of the eye, opens and closes to control the pupil size
  • cornea—a thin, film-like tissue that covers the eye
    • on its way to the pupil, light passes through the cornea
    • the cornea is mostly transparent; however, some light is also reflected from the cornea
  • sclera—the white part of the eye

Some eye tracking systems, such as ETVision, use a tracking technique known as “Pupil to CR” Tracking that uses the relationship between two eye features, the black pupil and mirror reflections from the front surface of the cornea (Corneal Reflections, or CRs), to compute gaze within a scene.

 

pupil-to CR- eye tracking technique
“Pupil to CR” eye tracking

Light from a pair of harmless near infra-red LEDs on the head gear illuminate the eye area. The near IR light is almost invisible to the user, so it does not cause a distraction, however it is visible to the eye camera. The mirror reflections of these light sources from the front surface of the cornea (CRs) appear in the camera image as a pair of bright dots. When the eye rotates in its socket, the center of the pupil moves relative to the spots. By comparing the relative position of the pupil and the CRs, the eye tracking system can compute the pointing direction of the eye visual axis relative to a coordinate frame centered at the scene camera.

During periods when the headgear remains stationary on the head, eye gaze direction can also be computed from pupil or CR position alone, and this can allow the system to continue to compute gaze when only a subset of the eye image features can be successfully identified. By computing the point at which the lines of gaze from the two eyes converge, the gaze point can be represented as spot on the scene camera image.

Since the geometry of the eye structures and the position of the optics with respect to the face vary somewhat from person to person, gaze computation accuracy can be improved by incorporating data from calibration points (points at which the person wearing the optics is known to be fixating a particular point on the scene camera image). Excellent accuracy is often achieved with a single calibration point, but can sometimes be improved with additional points.

Eye tracking has many specific applications for academic research, HCI, market research (ergonomics & design), sports performance, virtual reality, etc., and can easily be added to any study to increase feedback from participants in any environment.

Adapted from the ETVision Manual 

Ready to learn more?

Watch Eye Tracking Fundamentals now or visit our Webinars and Video Tutorial pages.

BIOPAC offers a wide array of wired and wireless equipment that can be used in your research. For more information on solutions for recording and analyzing life science signals and measurements, visit the Research > Applications section on the BIOPAC website.

Eye Tracking Insights

Try Not To Blink—This Won’t Hurt

What exactly, is eye tracking? Do I have to put on a helmet or stick something unpleasant into my eye? No, nothing so invasive, and not the least bit uncomfortable. Eye tracking is the process by which eye movements are recorded for the purpose of tracking where a subject is looking, what he/she is looking at, and the duration of the subject’s gaze on a given area. Eye tracking differs from electrooculogram (EOG) in that it records where and at what the subject is actually looking, whereas EOG primarily records the movements of the eye muscles. Rather than merely recording eye movement and position, eye tracking forges an invisible yet accurate connection between the subject and the objects within the subject’s field of vision. These “visual connections” of where the subject was looking during the study are clearly visible in the resulting data, as dramatic as tire tracks on an impressionable surface.

So how does eye tracking work? Using invisible near-infrared light combined with high-definition cameras, the eye tracking system projects invisible light onto the eye and records the direction from which it is reflected off the cornea. Eye tracking software is used to calculate the exact position and focal point of the eye. The sophisticated combination of eye tracking hardware and software allows for extremely accurate measuring and analyzing of visual behavior and fine eye movements. This makes it possible to create a detailed map of a subject’s field of vision and the specific visual elements honed in on by the subject. Eye tracking data is commonly acquired in tandem with other body signals for the purpose of determining the effects of what we are looking at has on our physiology. Common signals acquired during eye tracking studies are:

  • EEG (cognitive processes)
  • EDA (alertness)
  • ECG (anxiety)
  • EMG (muscle activity, conditioning)
  • EGG (pulse, respiration, temperature)

What are researchers looking for when conducting eye tracking studies? Eye tracking data is useful in a variety of different research fields including interface usability, reading analysis, psychological and emotional response, marketing research, training, clinical vision diagnosis, and more.

Eye tracking hardware mainly comes in two flavors. Screen based eye tracking involves having a subject sit in front of a computer monitor while being presented with various types of visual stimuli. A “bar type” eye tracker records the subject’s responses and interfaces with eye tracking software to present the stimulus and store the resulting data for analysis. BIOPAC’s AcqKnowledge software version 5.0.6 and higher, along with the BIOPAC MP160, MP36R, or Wireless Smart Center system, supports fully-integrated eye tracking functionality*. Rather than having to learn a second software program, the familiar AcqKnowledge interface has been extended to incorporate the EYE-TRACK-BAR and EYE-TRACK-BAR-XL remote screen eye tracking systems.

Mobile or “wearable” eye tracking systems utilize a pair of glasses with two types of built-in cameras. One camera faces the subject and tracks eye movements, gaze path, and other parameters, and a second camera (called a scene camera) records what the subject is looking at during the study. Mobile eye tracking allows the subject to engage in independent activities outside the lab, such as driving an automobile. Additional sensors record and log data from other body signals in real time, which can be loaded into the software for subsequent analysis.

For more information about eye tracking, we invite you to sign up for our free “Eye Tracking Fundamentals” webinar to be broadcast live on November 21, 2019 at 8:00 AM PST. Did you miss it or can’t attend? No problem. Follow the same link to watch it on demand.

*Eye Tracking Integration License for AcqKnowledge required.

Please also visit the following links for information about BIOPAC Eye Tracking products.

Eye Tracking Systems

Eye Tracking License

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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Neuroscience – A Brief History

What is neuroscience? In a nutshell, the study of neuroscience encompasses the physical and functional workings of the human brain and nervous system, drawing from a mix of cellular and molecular biology, anatomy, physiology, human behavior, and cognition. This field remains in a state of near-constant evolution, as the brain does not easily give up its secrets. Although the brain is home to a hundred billion neurons (brain cells), with nearly a quadrillion connections linking them, we have yet to fully and deeply understand the full breadth of a single cell.

But when and how did neuroscience originate? We know that as far back as 7,000 years ago, healers were boring holes into the skulls of their companions, a process known as trepanation. One can imagine the grim determination these ancients exhibited in their efforts to understand and relieve suffering, even if it was only with the intent of exorcising evil spirits. And it’s harder still to imagine how boring into someone’s living skull without anesthesia could possibly offer any measurable relief from suffering. However misguided these ministrations were, it’s clear that even millennia ago, the brain was recognized as an organ of great physiological significance.

For centuries, conventional wisdom recognized the heart as the seat of human consciousness. The Greek physician Hippocrates challenged this hypothesis, believing the brain to be the center of intelligence, yet the heart continued to hold sway with physicians and healers until long beyond Hippocrates’ time. This view persisted until the Roman physician Galen consistently observed that brain injuries sustained by gladiators often resulted in a marked decrease in cognition and mental acuity. (These injuries possibly foreshadowed today’s phenomenon of NFL CTE injuries.) Gradually, the brain began to take its rightful place in the pantheon of human physiology.

During medieval and Renaissance times, continuing important discoveries about the brain helped lay the foundation of what would become modern neuroscience, much of this new knowledge gleaned through illicit dissections, or by examining the brains of executed criminals. It’s safe to say that much scientific discovery—including that of human physiology—was hobbled by the religious constraints of the day. It wasn’t until the late 18th century, when Luigi Galvani observed the electrical activity of muscles and neurons, that key indicators about brain function became more apparent. Observations during this period often raised more questions than answers, however.

The 19th century brought further advances in the study of the brain and nervous system, notably by Emil du Bois-Reymond, who successfully demonstrated the electrical properties of nerve signals, and Paul Broca, who discovered through his pioneering work with brain-damaged patients that different regions of the brain were responsible for specific functions. This was later borne out by the German anatomist Korbinian Brodmann, who mapped the human cortex into 52 distinct areas, along with their corresponding functions.

In the 20th century, and particularly since the 1950s, neuroscience has evolved into an increasingly wide-ranging discipline, incorporating the brain and nervous system on a molecular level. This gave rise to many different types of neuroscience, which include affective, behavioral, molecular, cellular, clinical, computational, and a great many more. As the study of neuroscience has progressed, this field has produced no fewer than 19 Nobel Prize Laureates between 1904 and 2017. Neuroscience encompasses the most complex and sophisticated organ system in the body, a system that may possibly never be fully understood and certainly will continue to present wonders and challenges for centuries to come.

If you study neuroscience and want to learn more about how to get great data & meaningful life science measurements for human, animal, virtual, or MRI protocols, be sure to check out [button link=”https://www.biopac.com/webinars/” type=”small” newwindow=”yes”] BIOPAC Webinars[/button].

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T4 Conference Wrap-up

August is a month of barbecues, baseball, and last-minute vacations against the backdrop of a fading summer, and the eighth month of 2019 proved to be an equally exciting time at BIOPAC, with something of a pleasant vacation thrown in. On August 12-14, BIOPAC hosted its 2nd Biennial “Tools, Trends, Techniques, and Technology” Human Physiology Conference, known as “T4” to our friends and partners around the world. This three-day event, first held in 2017, featured lively, informative sessions hosted by BIOPAC staff, partners, noted academics, and industry experts, and covered a wide range of physiological techniques and disciplines. Over 150 attendees joined BIOPAC at the 2019 T4 Conference staged once again at the beautiful University of California at Santa Barbara campus. Participants and instructors winged in from China, Australia, Germany, Sweden, Italy, Spain, U.K., Ireland, and Egypt, as well as from wide regions of the U.S and Canada to soak up the idyllic surroundings of this ocean-side campus.

The focus of BIOPAC’s T4 Conference was to provide a fun, relaxed environment while hosting nearly 40 hands-on, human physiology training workshops chaired by over 20 distinguished instructors from around the globe. One of the many conference highlights was the “Mindfulness, Meditation, and Measurement: Mindfulness Exercises in Physiological Monitoring” session, hosted by Dr. Allan Weiss of the University of Southern California and  BIOPAC Co-founder and Director of R & D Alan Macy. These sessions, conducted in two parts over a two day period were booked beyond capacity, even though the early morning fog hadn’t yet lifted from the campus skyline.

The varied additional sessions covered a range from the basics, “Setting Up Your Lab, Getting Great Data and Troubleshooting,” (hosted by Dr. Terry Blumenthal of Wake Forest University, and BIOPAC’s Alan Macy and Tim Cook), and “Creating Your Own Lessons Using BSL PRO,” (hosted by Dr. Taffeta Elliot of the New Mexico Institute of Mining and Technology), to exciting new technologies such as “Integrating Screen-based Eye Trackers with AcqKnowledge,” with Keith Jackson of BIOPAC partner company EyeTech, BIOPAC CEO Frazer Findlay, and BIOPAC Engineering Manager Ed Peterlin. Additional wide-ranging physiological disciplines were also covered, including MRI techniques, stimulation, and exercise physiology. All sessions were conducted using BIOPAC hardware and software systems, as well as platforms provided by BIOPAC partners such as Cedrus, fNIR, WorldViz, Psychology Software Tools, and CNSystems. At the end of each day, it was time to relax and unwind with a beverage of choice, a a walk along the beach, and some good conversation. Each evening featured excellent meals and camaraderie in the relaxed yet elegant environment of some of Santa Barbara and Goleta’s most stunning surroundings. After three great days of immersive sessions, it came time for everyone to part ways, having forged new collaborative partnerships and an enhanced knowledge about the full potential of BIOPAC and BIOPAC partner products.

You don’t have to wait for T4 2021 to learn more about life science data—watch Fundamentals of Physiological Data Recording now!

For a closer look at T4, and a preview of what is sure to be an exciting 2021 event, we invite you to visit our T4 Human Physiology Conference page.

Looking for additional resources, tips, tricks, and expert advice on BIOPAC and BIOPAC Partner products? Please also visit our Webinars and Video Tutorial pages.

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.

Best Practices for Recording & Analyzing Data

Over the past several years, tools and techniques for recording and analyzing physiological data recording have seen steady and marked improvement. Modern life science data acquisition systems such as the MP160 System and powerful research-grade software suites such as AcqKnowledge bring high-end physiology tools within reach of the smallest lab. Even with continuing advances and reduced margin for error, it remains prudent to follow some fundamental guidelines for maximizing data quality and clarity.

Preparation is important. First, invest time exploring the system if it’s new or unfamiliar. An overview of the documentation, training videos, and available webinars, as well as some practice runs with the hardware and software will save time and effort when the time comes to conduct a study. This will also build proficiency at identifying the differences between good and poor data.

Next, familiarize yourself with the type of electrodes and/or transducers necessary for the physiological signals you will be acquiring, which includes proper electrode and skin site preparation. For example, gently abrading the skin prior to applying electrodes is normally recommended for most signal types, except for electrodermal activity (EDA), in which case it’s vital to NOT abrade the skin beforehand. It is also helpful to wait at least 5 minutes before starting a recording, which enables the electrode gel to be absorbed into the skin, helping reduce the impedance.

Performing an impedance check to ensure that the electrodes are making good contact with the skin is also highly recommended. This task is made easier by using an Electrode Impedance Checker (such as EL-CHECK), a simple device for quickly measuring the resistance between the skin and the electrode that provides an LED readout of the skin/electrode contact quality. If the resistance is too high (indicating poor contact) proper adjustments can be made before starting an experiment.

For certain signal types, excessive participant movement can introduce unwanted artifact into the signal, resulting in poor or skewed data. Make sure the participant remains as still as possible during studies involving these signals. Using tape to attach the electrode leads to the skin and keep them from moving excessively can also be helpful.

A thorough check of the system and all connections, cameras, and other hardware is important, so that any problems with equipment or setup can be addressed in advance, thus avoiding a show-stopping issue in the midst of an experiment. This would include performing a pilot study with trained personnel in order to head off any unforeseen issues with the data collection.

Creating a lab setup conducive to a relaxed environment for the participant and technician alike will yield better results. This means eliminating clutter, noise, and other distractions that can affect comfort and attention span. Some labs even avoid having their staff wear lab coats because this can heighten participant nervousness.

Keeping detailed notes on successful lab setups is also helpful and will streamline the preparation process for future experiments. Additionally, creating and saving graph templates for regularly-repeated experiments will save further time and effort.

For more about the fundamentals of recording great data, we invite you to view this free on-demand webinar Fundamentals of Physiology Recording.

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.

Photo by John Schnobrich on Unsplash

ECG – The Little Wave You Can’t Live Without

For millennia, ancient healers across the globe long recognized the human heart as immeasurably vital to human life. Other organs may take an occasional time out, but not the heart. This sinewy fist-sized pump contracts and relaxes an average 60 to 80 beats per minute and faithfully repeats this cycle some two and a half billion times over an average human lifespan, constantly driving and recirculating lifeblood through 100,000 miles of veins, arteries, and capillaries. It’s a monumental task that we take for granted, but if the process stops for more than a few minutes, so will this mysterious force we call life.

It’s intriguing to consider the wonder with which the ancients must have contemplated this organ that thumps so audibly. They knew it was of critical importance, and over the centuries learned its form and surface physiology, but what did they imagine animated it? What force kept the heart moving so steadily and faithfully, while remaining implacably divorced from the consciousness of its host? (Go ahead. Try to stop your heart. On second thought, don’t.)

The answer, in a word, is electricity. Although the stethoscope, invented in 1816 by French physician René Laennec, augmented audible heart sounds, it wasn’t until 1901 that Dutch physician Willem Einthoven developed a “string galvanometer,” capable of reliably recording the heart’s electrical activity. Einthoven’s work established a standard configuration for recording the electrocardiogram (ECG) and garnered him the Nobel Prize in 1924. Because the ECG reflects electrical activity, it is a useful “picture” of heart normality or abnormality through the observation and analysis of various distinct components of the cardiac cycle. If there are interruptions of the electrical signal generation or transmission, the ECG changes. These changes can be useful in diagnosing changes within the heart.

The methods for recording ECG have become increasingly sophisticated with the advent of digital technology and have put state-of-the art acquisition and analysis of ECG within reach of not only clinicians, but also researchers and educators. Wired in-lab systems such as the BIOPAC MP160 System with AcqKnowledge software are widely used for Research applications, while the MP36 System with Biopac Student Lab software are the industry standard for physiology education around the globe. Wireless systems such as BioNomadix or BioNomadix Smart Center can be used to collect ECG and other body signals in an untethered environment and the BioNomadix Logger is a great solution for acquiring ECG and other body signals over extended periods outside the lab.

We have come a long way since our forebears contemplated the mysteries of the vital mechanical wonder that beats in every chest, and we now have a myriad of accessible options for unlocking its secrets.

For further exploration of ECG, we invite you to enjoy the following comprehensive free ECG webinars:

Recording Great ECG

HRV & RSA – Fundamental ECG Analysis Techniques

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.

 

Using fEMG for Facial Expression Analysis

Facial expressions, even at their most subtle, cover a wide palette of emotions. The study of these expressions can be approached several ways, including via a camera and facial mapping using FaceReader expression analysis software—but another common method for acquiring this type of data is through facial electromyography (fEMG).

fEMG is a relatively simple procedure that focuses on recording the activity of two specific sets of facial muscles:

  • zygomaticus major (cheek muscle used for smiling)
  • corrugator supercilli (forehead muscle associated with frowning and negative emotions such as anger, fear, and disgust).

While parsing a subject’s nuanced emotional state can be tricky, zygomaticus and corrugator muscle activity are highly reliable indicators of the physiological components of smiling or frowning. Even tiny variations of expression barely discernible in video are detectable via fEMG, as the slightest tension and release of the zygomaticus or corrugator muscles will be reflected in separate channels in the fEMG data.

So, how do we acquire good quality fEMG?

Since the zygomaticus and corrugator muscles on each side work in tandem during natural smiling or frowning, it’s only necessary to apply electrodes to one side of the face. It’s also important that one—and only one—ground electrode be used; for fEMG, ground is normally applied near the corrugator electrodes.

  1. First, the facial skin needs to be properly prepared by gently cleaning with an alcohol wipe, after which it’s recommended to apply a skin prep solution called ELPREP to enhance signal quality.
  2. Select and apply reusable (EL254, EL654) or disposable (EL513) electrodes.
  3. Before recording fEMG data, it’s also highly recommended to verify that the impedance of the attached electrodes falls between between 5 and 10 KOhms. This is easily achieved through the use of an electrode impedance checker called an EL-CHECK, which takes the guesswork out of proper electrode adhesion
  4. Connect the appropriate lead to the selected amplifier. The type of recommended electrode leads will depend on whether the setup uses

With the proper setup and equipment, acquiring great fEMG data is as easy as smiling.

To learn more, we invite you to visit our webinar page for these and other free, on-demand webinars that detail methods for recording and analysis of fEMG data:

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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