public  class MainViewModel:
        BaseViewModel, IDisposable
    {
        private  SerialPort _serialPort;

        public MainViewModel()
        {
            _serialPort = new SerialPort("COM3", 19200, Parity.None, 8, StopBits.One);
            _serialPort.Open();

            _serialPort.DataReceived += _serialPort_DataReceived;
            _serialPort.ErrorReceived += _serialPort_ErrorReceived;

            CloseConnections = () => {
                _serialPort.Close();
                _serialPort.DataReceived -= _serialPort_DataReceived;
                _serialPort.ErrorReceived -= _serialPort_ErrorReceived;
            };

        }

        private async void _serialPort_ErrorReceived(object sender, SerialErrorReceivedEventArgs e)
        {
        }

        private async void _serialPort_DataReceived(object sender, SerialDataReceivedEventArgs e)
        {                
        }

        public void Dispose()
        {
            Debug.WriteLine("I was disposed________________________________________");
        }

    }

 protected override void OnStartup(StartupEventArgs e)
        {
            var serviceCollection = new ServiceCollection();
            ConfigureServices(serviceCollection);
            ServiceProvider = serviceCollection.BuildServiceProvider();
            var mainWindow = ServiceProvider.GetRequiredService<MainWindow>();
            mainWindow.DataContext= ServiceProvider.GetRequiredService<MainViewModel>();          
            mainWindow.Show();
        }

    private void ConfigureServices(IServiceCollection services)
        {
            services.AddSingleton<MainWindow>();
            services.AddSingleton<MainViewModel>();
        }