Our group's mission is to develop new microfabrication technologies and device architectures that enable microscale integrated systems. Our expertise is in micromachined high-intensity ultrasonic actuators, sensors, and radioactive thin films for MEMS. The technologies have allowed us to investigate microscale effects in the following areas:

  ultrasonic surface micromachine actuation

Piezoelectric actuation generates large forces but small displacements. Hence, it scales well to the micron scale. Traditional approaches have been to use piezoelectric thin films to actuate surface micromachines. We have focused on using bulk PZT piezoelectric ceramics to excite surface micromachines. We have developed a process for laser-cutting PZT ceramics to obtain high-aspect ratio piezoelectric cantilevers. They can be coupled to surface micromachined structures through the substrate or though magnetically extruded pillars to silicon-nitride diaphragms. This architecture allows for fast integration of micromachines made from any process to PZT.

We have also used surface micromachine excitation to achieve battery-compatible ultrasonic micromotors, parallel assembly of micromachined flaps, and ultrasonic destiction.

  ultrasonic microfluidics

Our group also investigates methods for ultrasonic manipulation of liquids using nonlinear acoustic streaming and radiation forces. Using micromachines ultrasonically actuated with bonded PZT ceramics, our group has realized sample concentrators using vortex generators and used multidimensional ultrasonic radiation forces to separate particles by size in a battery-compatible platform. This new ultrasonic chromatography can be applied to not only separating biological entities down to the nanoscale, but also to assemble hybrid biological and inorganic micromachined particles.

  radioactive thin films for micropower

Radioactive thin films produce alpha, beta, or gamma decay which can be used to power MEMS: in a way, they are nature’s batteries. Our group is the first to demonstrate the use of radioactive thin films to realize a self-reciprocating cantilever that can potentially self-actuate for hundreds of years. After the demonstration of the self-actuated cantilever, we also demonstrated a self-powered actuator with RF-pulse output using piezoelectric actuators. We believe that there is no ongoing research in this area elsewhere.

In addition to creating electromechanical energy, radioactivity can be used as a photon source as well. Beta decay can excite atoms or molecules, causing them to emit light as they relax. This same process can also produce metastable states of atoms, an effect which is being studied for exploitation.

We are developing components of a chip-scale atomic clock based on radioactive thin films as well. We believe that our solutions will facilitate in lowering the power budgets of integrated systems. In other words, by having on board a source of 10-100 keV electrons, one does need to worry about generating high voltages for electrostatics and ionization required for so many MEMS systems. A hybrid power system of a 3V battery with radioactive battery sources will enable a new degree of integration of capabilities in autonomous systems.

  silicon-based ultrasonic surgical tools

We are using micromachining techniques to develop silicon-based surgical tools that use ultrasonic actuation to cut tissue. Such tools can sculpt tissue very accurately and can generate less heat compared to traditional ultrasonic cutting. Our group has also developed a process technology to integrate multiple piezoresistive strain-gauges on these surgical tools, enabling closed-loop control of the applied ultrasonic motion and the measurement of direct forces being applied to tissue. We are working on developing control algorithms, both in hardware and software, for precision surgical cutting with mechanical feedback to the surgeon.

  insect MEMS

In following our group's theme on ultrasonic incision of tissue, we are investigating whether insects use vibratory motion to cut tissue. We have developed piezoelectric and piezoresistive sensors to detect biting events of insects such as mosquitoes. Our data (unpublished) shows that mosquitoes do indeed use vibratory cutting at 100-400 Hz to try to penetrate the skin. Current work is focused on obtaining quantitative data on biting forces.

  MEMS bio telemetry

We are developing MEMS-based sensors to be inserted into the body for an extended period of time. The sensor will transmit information to a receiving unit outside the patient. We are using both RF and ultrasonic links to communicate piezoelectric sensor data. A particular project of interest is the telemetry from the bladder for ambulatory urodynamics.

  not research

Cornell Slope Day 2005: [1] [2] [3] [4]

Group dinner / Hang party Aug 2005: [1] [2] [3]

SonicMEMS Barbeque May 2006 [1] [2] [3] [4] [5] [6] [7] [8] [9]

          Ciao Pietro! Dec 2006 [1] [2] [3]