title: Proximity sensor recommendation to detect hand & blood
body: <p>My company is interested in designing a protection system for small industrial machines, where factory employees insert wooden objects that are then cut by these machines.</p>
  
  <p>The protection system needs to be aware of the presence of a human arm when inserted into the input-hall - the human arm will then put a piece of wood and the machine will cut the wood - however, the protection system needs to be able to detect the presence of <strong>blood</strong> in case for some reason the arm is cut - and in that case shut off the power of the industrial machine.</p>
  
  <p>I'm no expert on sensing technologies and as we are looking to hire one, I am asking for advice on the proper sensing technology that can fit these requirements.</p>
  
  <p>Capacitive sensing, as I understand - can not only detect the presence of an object - but also the type (e.g. <em>distinguish</em> human arms from blood) - can such technology be used for the purpose mentioned above?</p>
  
  <p>Thanks,<br>
  Arkadi</p>