Real-Time Heatmap display as sKan is on finger
:Circuit overview after the implementation of
Sample results display
Thermistor array and preconditioning PCBs
Preliminary Thermistor Calibration Setup
The sKan assists physicians and the average person with detecting melanomas by creating a thermal map of the region of interest on the skin. It provides a quantitative measurement to improve the purely qualitative and inefficient diagnostic method.
Melanoma is harmless if detected early, however, it still claims hundreds of thousands of lives around the world annually. It accounts for 80% of all skin cancer-related deaths. Research from clinics in the U.S shows that only about 1/50 skin biopsies actually had cancer. These two factors mean that melanoma is misdiagnosed and often detected too late. Investigating current diagnosis methods, we discovered it is still a purely qualitative test, based only on visual inspection. We aim to add a quantitative measure to this procedure to improve its accuracy and decrease the delayed discovery.
The design consists of a transducer, a conditioning circuit, an analog to digital converter and a software processor.The transducer is an array of thermistors placed on the region of interest as it returns to ambient temperature after being cooled. As the temperatures of each thermistor varies, the voltage through the circuit changes, sending a signal through a specific conditioning circuit to filter and amplify the signal before becoming digitized by a microcontroller. The signal is then sent to a computer through a serial connection to be formatted and fitted to thermistor parametric curves. Time synchronous averaging, temperature variation detection and spatial validation are conducted on the signal. The results are displayed through a heat map and a temperature time plot, paired with a statement of the findings. The analysis reports the location and range of temperature differences on a temporal metric.
Initially, the design consisted of a scan of some sort that could provide spatial and thermal data to a computer to be processed in order to identify any consistent findings. After exploring different methods such as; infrared, thermocouples, and imaging processing, we determined thermistors were the best data acquisition transducer to use. Due to the difficulty of measuring an unknown resistance, the conditioning circuit underwent several revisions before a Wheatstone bridge topology was used. The circuit and its components are specific to the range of temperatures the thermistors are expected to face. Initially, the prototype used a MSP430 TI microcontroller before the switch was made to an Esduino Xtreme to increase digital quantization and data formatting ability. After testing the circuit with breadboard and wires, a PCB was designed and implemented into the prototype and placed in a housing structure created in AutoCad to reduce noise. With the latest prototype, the software processing can determine which thermistors showed a significant temperature difference throughout the duration of the testing in a few minutes. Due to the type of thermistors currently used the prototype is built to be able to accurately detect differences as low as 0.6 degrees.
After comparing our design to designs that are commercially available and those still in research phases, our design is the only solution that uses physical contact with low-cost thermistors as the temperature transducer to acquire data. Commercially available solutions consist solely of image processing which presents extremely high false-positive levels. Other similar designs used in research involve infrared imaging of suspicious regions, however, the infrared cameras used cost tens of thousands of dollars. Our design is unique and the most economical while still providing a high level of accuracy.
We aim to develop and test this device till it receives medical approval so that it can be used as a clinical tool by physicians to assist with their diagnosis’. We also hope that one day the sKan can become a household device so that skin melanoma checks can be a regular and comfortable part of everyday life to decrease the number of victims of melanoma. We are currently examining ways to improve our design while interviewing physicians, oncologists, and dermatologist to get a better understanding as to where our device can fit in their practice.
The sKan won third place amongst Electrical and Biomedical engineering final year design projects at McMaster University in 2017. The sKan has also won the Emerging Entrepreneur and the People’s Choice award at The 2017 Forge Pitch competition in Hamilton Ontario.