Flash drives are wonderful ways to save important data, but they are also terrible ways to lose important data. That is why you should encrypt every flash drive that holds any of your personal data. You can do the same with your MicroSD cards. You can only encrypt a flash disk or MicroSD card using a PC running Windows 8.1 Pro or Enterprise. But after the disk is created you can unlock it and use it on any Windows version.
To encrypt your flash drive or MicroSD card using BitLocker, right-click on the drive icon you want to encrypt in File Explorer, then click on 'Turn On BitLocker'. Enter a password, choose the encryption options, and wait until Windows finishes encrypting the current contents of the drive. You can then safely remove the drive or card and move it to a different machine. If you want the drive to unlock automatically on a PC after you sign in, choose that option when you enter the password to open it.