Multiply insert with laravel 5.3 dynamic form

I'm trying to make a multiple insert with Laravel 5.3 in a table as follows:

Form

{!! Form::open(['route' => 'demanda.store', 'class' => 'form']) !!}
<div class="form-group form-inline">
  {!! Form::label('ano', 'Ano:'); !!}
  {!! Form::text('ano', $ano, ['class'=>'form-control','readonly']); !!}    
</div>
<div class="form-group form-inline">
  @foreach ($unidades as $unidade)
    <div class="form-group">
      {!! Form::hidden('item_id[]', $items->id, null); !!}
      {!! Form::hidden('ano[]', $ano); !!}
      {!! Form::label('unidade', $unidade->sigla); !!}
      {!! Form::hidden('unidade_id[]', $unidade->id, null); !!}
      {!! Form::text('qtd[]', null,['class'=>'form-control','placeholder' =>'Demanda'])!!}
    </div>
  @endforeach
</div>
{!! Form::submit('Salvar', ['class' => 'btn btn-primary']) !!}
{!! Form::close() !!}

How would I get my controller to insert this data into my table, knowing that the fields in my table are:

  

• ano
  
• tem_id
  
• unidade_id
  
• qtd
  

Controller

public function store(DemandaFormRequest $request)
{
    $dataForm = $request->all();
    $insert = $this->demanda->insert($dataForm);
 }

I get the following error :

  

QueryException in Connection.php line 770: Array to string conversion