Starting Kit for Wearable?

Hi guys, I am a software engineer and I am working on a new wearable prototype (wristband kind).

At the moment I used an Arduino Uno starting kit to start to configure my Android and iOS SDK just to make some proof of concepts.

Right now I am in the phase of choosing the first development board for my physical prototype. The idea is to work on ARM Cortex A for low energy comsumption but also ARM Cortex M is interesting even if I believe that its power will blow away the battery in few days.

Before desigining any custom PCB I want to test out an ARM Cortex, plug my sensors, write the internal OS of the wearable and more forward from there.

What development kit do you suggest me to start with the evaluation of the ARM Cortex MicroCrontroller and mbed OS system?
I have few requirements to start with:

  • ARM Cortex Micro Controller
  • BLE Bluetooth
  • OLED display (touch or non touch)
  • Memory to save information
  • LiPo battery
  • Possibility to test sensors (gyro, vibrations, hearth pulse)

About the sensors I don't really need a development board with already a gyro or other sensors in it. But I want the possibility of tests my own sensors with mbed OS.

It would be nice if you can point me to some development board kits like the Arduino Uno. Then from there my plan is to slowly design various versions of my custom PCB as soon as I have a stable prototype done with the development board.

Thanks