The main idea behind this project is to use sweat as a non-invasive method of determining blood glucose level. An oximeter sensor that is able to measure heart rate and oxygen saturation was also added. The final device functions as a health tracker (or vitals tracker) called “Vitality meter”, which is able to track blood glucose levels, heart rate, and blood oxygen saturation.
Initially, we were looking at only using sweat to determine the blood glucose level, but with further research, we found that this method is less reliable and can only be used to supplement direct blood glucose measurements. Hence, we decided to incorporate both sweat and blood as options for blood glucose testing. The use of sweat for blood glucose testing can reduce the reliance on the invasive method of obtaining the blood for direct blood glucose measurements.
To start off with the project, we decided to look at the glucose concentration ranges for healthy and diabetic patients and found the following concentrations:
For Blood
| Hypoglycemia | Normal | Prediabetes | Diabetes | |
| Before meal | <4.0 mmol/L | < 6.1 mmol/L | 6.1-7.0 mmol/L | >7.0 mmol/L |
| 2h after meal | – | < 7.8 mmol/L | 7.8-11.0 mmol/L | >11.1mmol/L |
Values were obtained from HealthHub and National University Hospital
For Sweat
| Normal | Diabetes |
| 0.06-0.11mmol/L | 0.01 – 1.0mmol/L |
Values were obtained from the National Institute of Health
We also decided to look at the different circuit components needed for the glucometer. We referenced 2 other projects that have designed and built blood glucometer circuits:
- Hackaday.io Open Source Arduino Blood Glucose Meter Shield
- University of Texas at El Paso Intro to Electrical/Computer Engineering Module 6: Glucose Sensor
With all this research in mind, we designed our own schematics, PCB and case. The workflow of the project is shown below.
Let’s take a look at an overview of our final product. Firstly, we have our printed circuit board that does all the necessary measurements and can be powered by a wireless power transmitter or any phone with Qi wireless charging. It can also be powered through USB. The PCB is housed in a casing which contains a Velcro strap. This can be used to tighten a finger on the oximeter sensor for blood oxygen level and heart rate measurement. Magnets are also present inside the casing to align the transmitter and receiver for efficient power transfer. Using Bluetooth, the measurements are sent to an Android App which displays the result. More details can be found under the design specifications section.
