public async void StopListening()
        {
            HeartbeatAnimation.Stop();
            var sensor = bandClient.SensorManager.HeartRate;

            sensor.ReadingChanged -= SensorReadingChanged;
            await sensor.StopReadingsAsync();

            bandClient.Dispose();
            StartAppear.Begin();
            HeartbeatOutput.Text = "0";
        }
        async void SensorReadingChanged(object sender, BandSensorReadingEventArgs <IBandHeartRateReading> e)
        {
            try
            {
                if (e.SensorReading != null)
                {
                    this.Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
                    {
                        HeartbeatAnimation.Begin();
                        HeartbeatOutput.Text = e.SensorReading.HeartRate.ToString();

                        StatusBar.GetForCurrentView().ProgressIndicator.Text = "";
                        StatusBar.GetForCurrentView().ProgressIndicator.HideAsync();
                    });
                }
            }
            catch (Exception ex)
            {
                Debug.WriteLine("Error reading/sending data: {0}", ex);
            }
        }