The paper presents a very high sensitivity transimpedance amplifier in standard CMOS 0.35 mum technology suited for sensing current signals from molecular and nanodevices systems. The circuit, based on an integrator followed by a differentiator configuration, features i) a low-noise time-continuous feedback loop to cope with possible standing currents from the device under test as high as few tens of nA without limiting the signal dynamic range; ii) active current-reducers to implement very high value equivalent resistances of hundreds of GOmega with high linearity irrespective to the current direction and characterized by a shot noise current level (2qI) which is, for low standing current, few orders of magnitude smaller than a physical resistor of equal value and iii) nested-Miller compensation networks to ensure strong stability over a bandwidth of few MHz. Thanks to the ability to draw large standing currents, the circuit is suitable for a use in biological systems where physiological medium is co-present. The measured input equivalent noise of 4 fA/radic(Hz) at about 100 kHz, recorded when the input dc current is lower than 10 pA, allows the chip to be used, among others, in impedance spectroscopy measurements at the nanoscale with a capability of detecting capacitance variations in sub-attofarad range to cope with the challenges of single-chip instrumentation.

Photonic technologies lack non-invasive monitoring tools to inspect the light inside optical waveguides. This is one of the main barriers to large scale integration, even though photonic platforms are potentially ready to host thousands of elements on a single chip. Here, we demonstrate non-invasive light observation in silicon photonics devices by exploiting photon interaction with intra-gap energy states localized at the waveguide surface. Light intensity is monitored by measuring the electric conductance of the silicon core through a capacitive access to the waveguide. The electric contacts are located at suitable distance from the waveguide core, thus introducing no measurable extra-photon absorption and a phase perturbation as low as 0.2 mrad, comparable to thermal fluctuations below 3 mK. Light monitoring with a sensitivity of -30 dBm and a dynamic range of 40 dB is demonstrated in waveguides and high-Q resonators, and for the tuning of coupled-resonator optical filters. This approach realizes a ContactLess Integrated Photonic Probe (CLIPP), that is simple, inherently CMOS compatible, non-invasive and scalable to hundreds of probing points per chip. The CLIPP concept provides a viable route to real-time conditioning and feedback control of densely-integrated photonic systems.

We demonstrate a method for quantitatively probing the local low-frequency dielectric constant of thin insulating films by nanoscale capacitance microscopy. The calibrated capacitance-distance curves are measured on the dielectric film and analyzed by using a tip-sample capacitance model here proposed. Applied to $\mathrm{Si}{\mathrm{O}}_2$ films as small as $1\times 1\mu {\mathrm{m}}^2$ area and $20–30\mathrm{nm}$ thickness, the method gives a dielectric constant on the submicron scale in agreement with the value determined on the large scale. The observed precision is set by the capacitance noise level of the instrument and the tip radius.

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