This letter presents the design, fabrication, and demonstration of a CMOS/microelectromechanical system (MEMS) electrostatically self-excited resonator based on a submicrometer-scale cantilever with ~1 ag/Hz mass sensitivity. The mechanical resonator is the frequency-determining element of an oscillator circuit monolithically integrated and implemented in a commercial 0.35 mum CMOS process. The oscillator is based on a Pierce topology adapted for the MEMS resonator that presents a mechanical resonance frequency of ~6 MHz, a relative low quality factor of 100, and a large motional resistance of ~25 M. The MEMS oscillator has a frequency stability of ~1.6 Hz resulting in a mass resolution of ~1 ag (1 ag = 10^-18 g in air conditions.

We have measured and calculated the magnetocaloric effect in macroscopic samples of oriented high-spin molecular clusters like Mn12 and Fe8 as a function of the temperature and both the intensity and the sweeping rate of the applied magnetic field. We have observed a high magnetic entropy variation around the blocking temperature of the magnetic moment of molecules and calculated the shift of the entropy variation and cooling temperature, with the sweeping rate of the magnetic field.

Monolithic mass sensors for ultrasensitive mass detection in air conditions have been fabricated using a conventional $0.35\mu \mathrm{m}$ complementary metal-oxide-semiconductor (CMOS) process. The mass sensors are based on electrostatically excited submicrometer scale cantilevers integrated with CMOS electronics. The devices have been calibrated obtaining an experimental sensitivity of $6\times {10}^{-11}\mathrm{g}∕{\mathrm{cm}}^2\mathrm{Hz}$ equivalent to $0.9\mathrm{ag}∕\mathrm{Hz}$ for locally deposited mass. Results from time-resolved mass measurements are also presented. An evaluation of the mass resolution have been performed obtaining a value of $2.4\times {10}^{-17}\mathrm{g}$ in air conditions, resulting in an improvement of these devices from previous works in terms of sensitivity, resolution, and fabrication process complexity.

This brief presents a fully integrated nanoelectromechanical system (NEMS) resonator, operable at frequencies in the megahertz range, together with a compact built-in CMOS interfacing circuitry. The proposed low-power second-generation current conveyor circuit allows detailed read-out of the nanocantilever structure for either extraction of equivalent circuit models or comparative studies at different pressure and dc biasing conditions. In this sense, extensive experimental results are presented for a real mixed electromechanical system integrated through a combination of in-house standard CMOS technology and nanodevice post-processing by nanostencil lithography. The proposed read-out scheme can be easily adapted to operate the nanocantilever in closed loop operation as a stand-alone NEMS oscillator

This paper presents a fully integrated pitch-matched PMUTs-on-CMOS array with high potential in catheter-based ultrasound imaging systems and capabilities to obtain resolutions under 100 μm. The system-on-chip consists of 7x7 AlScN PMUTs connected in a 1-D configuration where the six external rows are used to generate the acoustic pressure through three HV-pulser CMOS circuits, and the central row is used to sense the incoming ultrasound wave which will be amplified by a LNA CMOS amplifier. The experimental verification in a liquid environment gave, as a first result, a peak frequency of 7.7 MHz with a normalized pressure (ST) of 1.98 kPa _pp *mm*V ^-1 and receiving sensitivity (SR) of 3.3 V/MPa, respectively, competitive sensitivities in comparison with the state-of-the-art. In the second part, ultrasonic imaging for different wires with a minimum diameter of 25 μm was demonstrated as expected from numerical simulations. The system’s performance for ultrasound images was evaluated considering the product of the area and the resolution at 1 mm, giving competitive values compared to other reported ultrasound systems for catheter-based medical ultrasound imaging and the only one providing monolithically integration with the CMOS front-end circuitry.