LifeHand 1 (2008)   LifeHand 2 (2013) 
           
 

Duration of Experimentation

 

30 days
(including surgery)

 

30 days
(including surgery)

           
  Dimension of surgical incision   8 cm    15 cm
           
 

Number of implanted electrodes

 

 

4 electrodes in the median
and ulnar nerves

 

4 electrodes in the median
and ulnar nerves

           
 

Type of electrodes used

 

 

 

 

 

 

tf-LIFE (thin-film Longitudinal Intra-Fascicular Electrode) 

Biocompatible electrodes to be placed lengthwise on the nerve

 

TIME (Trasverse Intrafascicular Multichannel Electrode)

Biocompatible electrodes to be placed across the nerves in order to increase the contact points with the nerve fibres and increase communication with the central nervous system

           
  Diameter of contacts   80 micrometres   80 micrometres
           
 

N° of electrode contacts (active sites)

 

12 per electrode
(8 + 2 controls + 2 grounds)

 

16 per electrode
(14 + 2 grounds)

           
 

Material used for the contacts

 

 

Platinum on a sub-layer
of polyimide

 

Platinum and iridium oxide
on a sub-layer of polyimide

           
 

Potentially injectable electric charge

 

Approximately 4 nano-Coulombs

 

120 nano-Coulomb

           
 

Type of stimulation in order to move prosthesis

 

 

 

Neural impulses from
patient’s brain via connection
with intraneural electrodes

 

Myoelectric impulses arriving
from five surface electrodes
placed on muscles
of patient’s left forearm

           
 

Method of extracting spikes
from electrodes

 

Acquisition from one channel
at a time

 

 

Simultaneous acquisition
from several communication
channels with peripheral nerves

           
 

Tactile feedback from the hand to the patient

 

 

Absent

 

 

Present (2 tension sensors
placed within fingers
of the prosthesis)

           
 

Environmental conditions
of the experimentation

 

 

Biomechatronic hand placed
on a surface remotely
connected to the implanted
electrodes

 

Biomechatronic hand
directly attached to
the patient’s socket on
the forearm of amputated limb

           
 

Main abilities observe
during experimentation

 

 

 

 

 

 

 

 

 

Ability to move fingers through
neural impulses so as to make
three movements:

  • claw
  • small finger movement
  • fist

 

 

 

 

 

Precision control and
manipulating abilities through
the prosthesis in order to:

  • recognize the position of an object in relation to the hand 
  • recognize different consistencies of the objects 
  • recognize the basic shape of objects
  • apply the correct strength to hold objects
  • fine modulation of applied force over objects