Soft MEMS for sensors, actuators and energy

Development of an artificial lateral line system

A flow sensing system based on an artificial hair cells has been developed and a data analysis algorithm has been set up. Our flexible artificial hair cells take advantage of the material stress difference among constituent nitride-based layers and piezoresistive properties of strain gauges.

We designed and developed multi-parameter freestream flow measurements which provide information about:

  • local flow velocities as measured by the signal amplitudes from the individual cantilevers
  • propagation velocity
  • linear forward/backward direction along the cantilever beam orientation
  • periodicity of pulses or pulse trains determined by cross-correlating sensor signals.

A real-time capable cross-correlation procedure was developed which makes it possible to extract freestream flow direction and velocity information from flow fluctuations.

Our aim is to apply our single sensors and/or artificial lateral line as a method for flow sensing -based control of drones, underwater autonomous vehicles and automotive. All applications are based on the observation that flow sensing could be considered a sort of “distant touch hydrodynamic imaging” capability, replacing vision in case of harsh environments where the eye sense is strongly limited, due to high velocities or dark surroundings. This system can potentially improve sonar and vision systems, equipping manned vehicles and autonomous vehicles such as self-driving cars.

Energy harvesting from fluid flow in air and water

Energy harvesting topic has a huge potential since “Energy autonomy” and green energy mass production with low environment impact (even in terms of visual invasiveness), body implantability and acoustic noise, would set a new standard and paradigm in renewable energy technologies and applications.

This activity is aiming at developing:

  • A biomimetic design of flapping piezo-MEMS let us envision their application to wind energy scavengers integrated in architecture and buildings or hidden in natural environments. This will be applied to large-scale production of energy from wind and fluid flow to establish a green and low impact alternative to wind turbines and to produce energy from sea waves and water currents. This technology also matches the need and challenge in the powering and improved autonomy of remote sensors (IoT), inaccessible/implanted devices and unmanned autonomous vehicles (UAV).

  • Soft piezoelectric sensors on ultrathin and plastic substrates for implantable sensors and energy harvesters. The ultimate goal is to realize and test prototypes of thin films to be transferred on skin as active tattoos, to be integrated in patches or wristbands for real time monitoring of sport performance and health parameters or to be implanted in biomedical implanted devices, such as cardiac pacemakers, to increase their battery life or to enable battery-free operation. Soft acoustic nano-sensors could be applied for endoscopic applications in biomedical diagnoses.

Flexible Piezoelectric devices for acoustics applications

Several researchers worked on realization of flexible inorganic piezoelectric materials as high performance flexible energy harvesting systems but relatively little effort has been devoted to actuate membrane–based transducers for acoustics communications and biomedical applications.

This activity is aiming at developing underwater acoustic projectors and hydrophones. AlN/Polyimide-based membranes can combine both sensing and actuating mechanisms to obtain efficient acoustic wave generators and acoustic sensing in underwater environment for the development of sensing and communication in underwater UAVs and robots.

This combination is promising for establishing communication in underwater robotics suggesting a potential new paradigm for robotic swarming and underwater security and threats’ monitoring. For example, high-resolution active and passive matrices of acoustic pixels are very promising for active and passive sonars in UAVs and robotics.

Tactile sensors and actuators

The importance of the sense of touch as a mean of knowledge is boosting the research towards the development of devices able to collect information on parameters such as texture, roughness, shape, stiffness in reconfigurable mode and to produce forces to be felt by the real skin.

With the aim of producing a biomimetic artificial skin, soft materials and technologies can enhance the effectiveness of tactile perception.

A soft tactile technology and artificial skin is currently developed at CBN for robotics, since the sense of touch represents for a humanoid robot the mean to safely interact with people in unstructured environments.

Our anthropomorphic approach is based on piezoelectric AlN integrated on polymer to detect different type of forces: normal, shear, static and dynamic as in human mechanoreceptors. By integrating multiple functions in single devices, this approach is enabling a compliant and efficient technology for artificial skin, leading to a reduction of the density of needed sensors.