<style type="text/css">
    .onoff input.toggle {
    display: none;
}

.onoff input.toggle + label {
    display: inline-block;
    position: relative;
    box-shadow: inset 0 0 0px 1px #d5d5d5;
    height: 30px;
    width: 70px;
    background: #DC143C;
    border-radius: 30px;
}

.onoff input.toggle + label:before {
    cursor: pointer;
    content: "0a0 0a0 0a0 0a0 0a0 0a0 0a0  Não";
    display: block;
    color: #FFF;
    height: 30px;
    border-radius: 30px;
    background: rgba(19, 191, 17, 0);
    transition: 0.1s ease-in-out;
}

.onoff input.toggle + label:after {
    content: "";
    position: absolute;
    height: 30px;
    width: 30px;
    top: 0;
    left: 0px;
    border-radius: 30px;
    background: #fff;
    box-shadow: inset 0 0 0 1px rgba(0, 0, 0, 0.2), 0 2px 4px rgba(0, 0, 0, 0.2);
    transition: 0.1s ease-in-out;
}

.onoff input.toggle:checked + label:before {
    cursor: pointer;
    width: 70px;
    content: "0a0 0a0 0a0 Sim";
    color: #FFF;
    font-family: 'Arial';
    background: #13bf11;
}
.onoff input.toggle:checked + label:after {
    left: 40px;
    box-shadow: inset 0 0 0 1px #13bf11, 0 2px 4px rgba(0, 0, 0, 0.2);
}
#estado{ font-size: 14px; font-weight: bold;}
</style>

<table class="table table-striped">
 <thead>
   <tr>
     <td>Nome</td>
     <td>Ativo?</td>
   </tr>
  </thead>
  <tbody>
<?php
...
while($pe = mysqli_fetch_object($sql))
{
?>
   <tr>
     <td><?php echo $pe->Nome; ?></td>
     <td>
       <div class="onoff">
         <input type="checkbox" class="toggle" id="onoff">
         <label for="onoff"></label>
         <input type="hidden" name="Avisar" id="campo1" value="0">
       </div>
    </td>
<?php
}
?>
 </tbody>
</table>

<script type='text/javascript'>
//<![CDATA[
window.onload=function(){
var onoff = document.getElementById('onoff');
onoff.addEventListener('change', function() {
    estado = this.checked ? 'S' : 'N';
    var campo = document.getElementById("campo1").value = estado;
    $.ajax({
       data: {
           estado: this.checked,
           campo: campo
       }
   }).done(function(msg) {
   });
});
}//]]>
///////////////////
</script>