Which sensor to use for 14-day clinical trial study?
we are conducting clinical trials early next month. And we are interested in measuring people's activity (walking, standing, running, being jittery, eating/drinking, driving, ...), their body position (standing, laying, sitting, ...), and we also want to see if we can get their breathing patterns (fast shallow breathing, fast deep breathing, slow shallow breathing, slow deep breathing, ...). The study is running for 14 days and the sensor will continuously be connected (Bluetooth) and steaming to our Android app (our phones support Bluetooth 4.2 and LE. We are using Xiaomi Redmi 4X devices with 3GB Ram and Android 7 with MIUI 9 skin). The sensor should be small since we are asking people to wear it around their chest.
I was informed that accelerometer sensors consume very little power and the MetaMotionC with only accelerometer activated can comfortably last 14 days. But I was informed that the gyroscope consumes a lot of power.
One question is, for the above mentioned purpose, do we need all sensors (accelerometer, gyroscope, magnetometer) activated, if not which ones are required to get the information we need?
Another one is, does does anyone have experience with MetaMotionC or R and longer term bluetooth steaming? How is the battery life?
If the battery lasts for 7 days continuous use on all 9-axis with MetaMotionC I think that would be okay to ask subjects to change the battery once. Else we might have to either not use all 9-axis or we could use MetaMotionR and ask them to plugin the USB cable for a couple hours daily.
Which solution would you suggest we should take? We prefer to get it right the first time around, because it's quiet demanding on the test subjects.
Than you kindly or all replies.
Accelerometer data should be sufficient but that needs to be tested by your team.
It's unlikely the battery will last 7 days with all 9-axes of data with the MetaMotion C due it being powered by a coin cell battery.
MetaMotion R can be outfitted with a larger LiPo battery, which will probably be necessary to get you to 7 days depending on how fast you are sampling the accelerometer. You will have to experiment to see how long the battery will last given your sampling parameters.
Probably MetaMotion R due to being able to add bigger LiPo batteries if needed.
Thank you Eric.
Where can I get the bigger liPo batteries?
You can probably find them at hobby stores like SparkFun.
I would recommend that you work with MbientLab to do a custom order if you indeed need a bigger LiPo. Before you even decide on that however, you should first test if the current battery is sufficient for your use case.
Hi Eric, that's a great idea. I will contact them and see, sadly we only need 10 sensors for the first trials so I am not sure if it makes sense for MbientLab. But I will definitely talk to them.
We have a program that promotes physical activity in the workplace. It suggests strategies to cut back on the periods of time that you remain seated and increase your active or walking time during working hours.
We work with an app that receives streaming data from metawear C. I tell you that the life's battery is around 90 days. but the sensor only connects for 8 hours a day, Monday from Friday. It would be perfect if it wasn't for
we have trouble with some mobile Os Android that unable to connect to MetaWear. Have an idea?