Hi I am an electronics engineer with 4+ years experience in biomedical electronics and embedded systems . In your Project you are using MCP3008As ADC. It has 8 i/p channels with 200k samples/s. Which is sufficient for reading analog channels for Temp, SpO2, and ecg. I have done many similar projects. I can provide you the codes for continuous reading of Spo2 and ECG along with Temp.
I need some more information , What type of sensor you are using for ECG and SpO2. How many channels you have for ECG 1 or 4 or 12. Also what SpO2 sensor you are using is it a PPG sensor?
Do you need the design of ECG sensor. I can Provide you a custom design for your requirement also.
regarding price is flexible .Please discuss in chat.