About ZenSnap® SmartRuler Technology


Transforming Millions of Mobile Phone Cameras to Viable Wound Size Measurement DeviceS Over night!

Why Did We Develop It?

When it comes to wounds or other skin lesion treatments, measuring the size is very important in achieving a good outcome. There are many expensive devices and options with laser or infrared ranging, but we thought there should also be a solution that’s affordable and reliable for everyone to use immediately.

As we set out to tackle the problem, we focused on the following clinical requirements:

  1. Implement the technique using inexpensive technology.

  2. Do not change current workflow.

  3. Do not introduce infectious or other medical hazards.

  4. Usable by anyone without any specific training and requiring no additional gear to hold the camera at specific angles or distance.

  5. Use the existing diagnostic software to measure and display the size (i.e., radiology workstations).

  6. Calibration without requiring additional technology such as transducers so that data can be read anytime in the future for the lifetime of the patient.

  7. Can also collect light and light color calibration data.

Testing with our Prototype 1

Testing with our Prototype 1

Current Workflow

In most wound photography today, there are commercial paper rulers that clinical users add to the pictures. We thought that if we make the ruler to contain additional computer detectable information, we could actually perform this without any additional equipment. Also the ruler itself can be discarded to prevent the spread of infection, like utilizing non-sterilized hardware size measurement devices from patient to patient.

Our Solution: Invention of Smart Ruler Plus Auto Calibration Algorithms

We have invented a smart ruler and algorithm to perform fully automated calibration that meets all our requirements. This technology is recognized as patentable and we were granted US Patent No. 10,169,882 B1 in December 2018.

  1. We use plain paper stock.

  2. It is the same workflow as using paper rulers that clinical users use today.

  3. Since it is disposable, users can only use it on a patient per encounter and discard the ruler.

  4. The algorithm we developed auto-corrects for the camera holding angles, so we do not require users to hold the camera in any specific angle or distance. So long as the photo is reasonably taken, we can compute a calibration.

  5. The resulting mm/pixel values are stored in a DICOM header, exactly the same way as they are stored in 2D CT or Ultrasound images.

  6. The photo can be taken with just about any inexpensive mobile camera as well as the most expensive SLR cameras.

  7. There is a standard gray color calibration spot in the center of the smart ruler.

Our Result

The final design, showing a good accuracy when measured on PACS workstation software. The strange edges on the photo are due to the perspective correction algorithm.

The final design, showing a good accuracy when measured on PACS workstation software. The strange edges on the photo are due to the perspective correction algorithm.

We are presently achieving about +/- 2 mm accuracy with this technology. Now we can ship (e.g., drop off via a drone operation) the ruler to anywhere users can transmit photos, and we can begin collecting high quality calibratable images from all around the world and use them for the lifetime of the patient.


The Future

  • Right now, on our app the calibration algorithm needs to be manually triggered. This can be easily corrected by the image recognition AI to first detect the presence of a smart ruler.

  • Currently the algorithm pipeline is not fully optimized, but runs in a general-purpose imaging processing program. By customizing the algorithm pipeline, we can achieve a significantly faster speed.

  • It is possible to know the lens characteristic of most major models of mobile phones and we can even improve the accuracy further.

  • This also can be used on any place where accurate size information in the photo must be preserved and so we will have some additional possibilities of marketing for other non clinical uses.

This solution is available on ZenSnapMD today.