Researches regarding neonatal imitation are of great clinical interest since they can provide evidences of an innate mechanism underlying action understanding; the study can be led through the analysis of infants' spontaneous movements, like grasping, that are recognized as markers of neural activity. To this aim, a portable and non-intrusive device has been designed and developed to measure infants' grasping during the presentation of specific visual stimuli. The device is composed of two soft handles with embedded pressure sensors. During trials action observation should produce an increase of the measured pressure exerted by the infant's hand, according to the imitation-based paradigm of the defined clinical protocol. The final prototype has been tested within a pilot study and it has been proved to be suitable for monitoring infants' imitation abilities, meeting all the clinical specifications in terms of size, weight, safety and sensitivity. Preliminary acquired results are a starting point to clarify mechanisms related to imitation and sensorimotor system growth. The present methodology could be employed to boosts investigation on the development of mirror neurons in infants.