Ionic 2 beta version - image upload issue on some android devices

Ionic Framework ionic-v3
1

I am using ionic 2 beta version and i used this code for image uploading on server.this works well on ios platform but it did not worked on some android mobiles.

I am using this angular code

this.model.image = event.target.files[0];
if (this.model.image) {
  let reader = new FileReader();
  var self = this; 
  reader.onloadend = function(readerEvt: any) {
    var aa = readerEvt.target.result;
    self.model.imageString = readerEvt.target.result;
  };
  reader.readAsDataURL(this.model.image);
}

Kindly suggest the better way of image uploading so it will work on all the mobile phones of ios and android