Is This Palm-Sized Device the Medical Tricorder For Our Times?

I am holding in the palm of my hand a device that can, in a matter of seconds, measure my ECG, my systolic blood pressure, my temperature, and my oxygen saturation. It’s really quite remarkable.

Two key cardiovascular vital parameters plus two parameters of keen interest in the COVID-19 era available to you in a device that weighs 4 ounces and has the dimensions of a 0.5-inch thick driver’s license!

Here’s the company’s summary of what it can do:

This rechargeable health monitor is small enough to put in a pocket. The monitor serves as a wearable thermometer for accurate forehead temperature readings, will track blood oxygen (saturation) levels and blood pressure (systolic), give a twenty second EKG reading, track your steps with its built-in digital pedometer, and save your data and upload to the cloud for historical records and reporting. With the optional wrist blood pressure cuff, you are able track both systolic (upper number) and diastolic (lower number) readings. Share your blood pressure and health readings with doctors or family members using the free BodiMetrics cloud.

The Performance Monitor (PM) is made by BodiMetrics and sells for $349.

I’m in the process of evaluating it more completely but within minutes of taking it out of the box I was able to easily record all of the claimed components.

A sweep of the sensor on the top of the device across the forehead yielded a temperature of 97.1 °F (that’s normal for me) which corresponded with the 97.2 °F I recorded from a digital oral thermometer at the same time.

After calibrating the PM with an arm cuff blood pressure I did a “body check” by placing the electrode on the left side of the PM against my left palm, putting my right thumb on the metal circle on the bottom front right, my right middle finger on the metal circle on the back and sticking my right index finger under the little latch in the right upper corner. (I know this sounds incredibly awkward but it was actually very intuitive and the positioning feels natural.) A pleasant woman’s voice plus screen graphics provide guidance during the process.

Within 30 second the device recorded a high quality single lead ECG from the electrodes I was touching with my left palm and right thumb and finger along with my oxygen saturation and blood pressure from the photoplethysmograph (PPG) on my right index finger. The ECG and PPG tracings are visible on the LCD screen along with measurements as they are rerecorded.

The data can be reviewed on the screen or uploaded to a free Bodimetrics app.

From the app the entire report can be shared to email, notes, messages, etc. in PDF form.

Readout of the Body Check session. Note that navigation is by a touchscreen.

Here’s the PDF of my initial report from this morning

The oxygen saturation (SpO2) was identical to a measurement immediately following using my pulse oximeter.

In addition to ECG, heart rate, systolic blood pressure, and oxygen saturation the device gives you respiratory rate (breath) and the RPP or rate pressure product (which is something we pay attention to when doing stress tests and is the product of systolic blood pressure and heart rate.)

When you’re done doing a “Body Check” you can have the PM “Relax Me.” While holding the PM and touching the various electrodes the device asks you to relax and breath in and out. It displays inspiration and expiration on the screen as you try to match the indicated waveform and rate. When completed a “relaxation index” is reported along with an estimate of heart rate variability (HRV).

I will need to do more testing of the individual components of this device. The ECG is free of artifact and Bodimetrics makes no attempt to interpret the rhythm. Although I have only tested them in my very limited and normal range the oxygen saturation and temperature seem accurate

I would not rely on the PPG mechanism in this or any device for an accurate blood pressure and I will have to test it further to assess the value and accuracy of this particular function. A recent review of PPG for BP assessment concludes that the technique holds great promise but is not yet mature.

The value or meaning of the relaxation index and the heart rate variability for any individual is unclear as I’ve discussed on my Oura ring posts.

For now, however, I’m really impressed with the number of things the PM can do in a tiny palm-sized format. I wasn’t exactly sure what Leonard “Bones” McCoy was measuring with his medical tricorder in Star Trek. Was it called the tricorder because it measured three things? If so, perhaps the PM should be called a quadracorder or even hexacorder.

Turns out (per wikipedia) “The word “tricorder” is a portmanteau of “tri-” and “recorder”, referring to the device’s three default scanning functions: GEO (geological), MET (meteorological), and BIO (biological).”

How many vital parameters does the PM measure?

It measures three of the four standard vital signs really well

  • heart rate
  • respiratory rate
  • temperature

It also measures the fourth vital sign, blood pressure with accuracy yet to be determined.

Accurate measurement of ECG I consider a major vital parameter so the PM reaches five

Oxygen saturation is a key vital parameter (especially in the COVID era) so the PM reaches six.

I’m not going to consider heart rate variability a vital parameter

The Performance Monitor, therefore, we will call a pentahexacorder (somewhere between five and six vital parameters recorded.)

May the PM allows us all to live long and prosper.

Skeptically Yours,



17 thoughts on “Is This Palm-Sized Device the Medical Tricorder For Our Times?”

  1. I know this is slightly off topic but I want to post an observation about wrist versus chestband for the accuracy of heart rate measurement.
    I regularly do a brisk 3km walk involving hills and stairs. I “know” the stairs are the harder part based on my breathing and general feeling.
    But my Garmin Forerunner 935 puts my maximum 133bpm after the stairs and later a higher reading of 142 on a later hill when i feel quite comfortable.
    But, with a chest band, my max at the stairs was 152, and the later hill 135.
    This is not the first time I’ve done this comparison with similar results. It would seem to me the wrist-only reading misses sudden peaks.
    I also do regular HIT weight training and the wrist-only is always substantially lower then with the chest band.
    If I am correct, this may be important information for people wanting to exercise but avoid a high pulse rate.
    I can’t post the graphs in this comment section

    • I’ve also found the wrist-based PPG devices frequently yield inaccurate heart rates with vigorous activity.
      I haven’t moved to a more accurate chest-based monitor because I’m not convinced I need continuous accurate read-out of my heart rate.
      However, this is an area I’ve been pondering a lot lately. I’m interested in exploring the concept of heart rate zones and cardiovascular conditioning.
      For example, a frequent question from patients is what heart rate zone should I be aiming for during my exercise? I’d like to have a solid recommendation on this based on scientific studies. I’m looking at peak heart rate versus heart rate reserve measures of CV conditioning and level of exercise. Both of these would require an accurate measure of peak heart rate during exercise.
      I will post on this soon. I’m curious what heart rate zones readers are aiming for (at least those who monitor HR) and what sources they are using to justify the zone.

      • Your study and recommendations would be most welcome by all Dr Pearson.
        My regular HIT elliptical program is 3min warmup, then (20s max, 2m recovery) by 3, total 10 minutes.
        I do not aim for max bpm, just observe it. Typical max is 160-170. I am 75, quintuple bypass 4 years ago.
        The maximum bpm for each sprint is higher than the last, but the pace is slower. The only way I can do the sprint is at 100%.
        What I would really like to have is the recovery periods being based not on time, but on the heart rate dropping to a certain level. At the moment it drops to say 140 before the next sprint and I wonder if that is too high. Please consider this component in your study.

    • I’ve touched on HRV a few times on this site.
      and have come very close to posting on it but ended up getting too wound up looking at original research.
      Here is my succinct summary:
      Whereas HRV when measured and reported out properly in research studies has shown some value as a metric of autonomic nervous system function and activity I can find no evidence that the HRV (typically a single #) reported out from devices such as Apple Watch or Oura ring reliably track any aspect of the ANS, have any value int measuring individual fitness, “readiness” or really any health parameter that would be useful or predictive of outcomes.
      I might post that statement and ask any reader to disprove it.

      • Thanks for a great blog!

        I agree that single or few HRV measurements every now and then do not provide any useful information. I have been using an Oura ring for HRV monitoring for three years now. For me the only useful information about HRV is to compare my recent rMSSD values to the longer term trend (average of nightly measurements over weeks or months).

        For example, a seven days of average nightly rMSSD value trend that is lower than 60 days baseline tells me that I am becoming more stressed compared to the past and this is possibly affecting my body´s ability to repair itself – whether that is because of mental stress, too much or too little exercise etc. This helps me to do lighter exercise when under stress and to stabilize the trend.

        I also know that my 60 days rMSSD baseline was higher two years ago and this gives me information that I have much potential to improve.

        I am not sure if HRV fits the hospital setting, but I consider HRV as possibly a useful tool for wellbeing or a patient’s own self monitoring tool after interventions. Maybe patients in myocardial infarction rehabilitation could use upward HRV as an indicator of making progress in rehabilitation? But, this conclusion might not be backed up by science?

        I would really like to read more about your thoughts on HRV!

        • Tero,
          thanks. My issue with HRV as expressed by rMSSD is that it is not a valid gauge of autonomic tone. Even if it were, there are no data to guide individuals on how to use it for useful purposes.
          Re HRV and useful information. Do you put more credibility in the average rMSSD dropping than how you actually feel?
          There is no data that would support the concept that a change in rMSSD gives prognostic or wellbeing information over and above say a resting heart rate.
          despite the development of much more sophisticated measures of autonomic tone from complex analysis of HRV data, no credible physicians in cardiology or medicine are utilizing HRV to monitor training effects, predict prognosis or guide therapy.

  2. As a personal user who monitors myself for Afib I like the instant analysis that the Kardia Mobile 6L and Apple Watch EKG’s provide. If I want a more detailed analysis by a Cardiologist I can send my suspect Kardia Mobile EKG to Kardia (directly from the app) and for $19 I will get a professional analysis back. From my user perspective I like to know what the readings mean because I’m no expert in interpreting the charts themselves. If I was fortunate to have an enlightened cardiologist like Dr. P, who likes and uses Kardia Pro then my strategy would change but finding one is, well, almost impossible.

  3. But does it emit the ‘TriCorder chirps when activated? If not, they missed a golden marketing point – not to mention therapeutic. A chuckle goes not astray in relaxing and stabilising the Patient !

  4. Good review by ACP. Being off 1 full degree seems like a lot to me. Price seems VERY high except for the few. I use $40 Omron wrist BP cuff for patients + cheap electronic thermometer. Wi Co V2-19 around, nice to have an O2 sat ability. HRS, MD, FACC

    • The temperature differed by 0.1 degree which I don’t consider significant, especially given one was forehead, the other oral.

  5. Worth the price for the average person? Not that 79 is average! Not worth it for me. But, as a retired Diplomat, former Peace Corps Volunteer, might have been happy to have it in remote locations.


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