CMOS-compatible MEMS processes and their application to the development of biosensors

The research activity developed during my Ph.D. program was focused on CMOS-compatible MEMS (Micro-Electro-Mechanical System) processes and their application to the development of biosensors. A first activity has been oriented towards the development of a technique to reduce the etching times and increase the freedom in the design of large suspended microstructures fabricated by bulk anisotropic etching of silicon. This goal was obtained by pre-patterning of the membrane with periodic convex-corner patterns. Different periodic patterns are proposed and analyzed, experimental release times for dielectric membranes are presented. The second activity research was focused on the design and fabrication improvement of a magnetically actuated microbalance for biosensing application. A CMOS-compatible protocol for covalent bonding of organo-functional silanes (to be used as link sites for biomolecular probes) on the microbalance surface was developed. The functionality of the device as a gravimetric sensor was verified. Moreover, a single chip integrated electronic oscillator based on the MEMS resonator was designed. A first prototype of circuit was implemented and characterized

Progetto e tecnologia di fabbricazione di un dispositivo MEMS magnetico per "energy scavenging"

Questo lavoro rigurda il progetto di un dispositivo MEMS magnetico in grado di recuperare l'energia dalle vibrazioni presenti nell'ambiente circostante. Inoltre é stata progettata anche la tecnologia di fabbricazione del dispositivo che si avvale di un nuovo metodo per liberare membrane di grandi dimensioni tramite attacco in TMAH bufferizzato in tempi brevi

Label-free detection of specific RNA sequences by a DNA-based CMOS BioMEMS

In this work we propose a resonant mass sensor based on a CMOS-compatible MEMS bulk technology, targeted at the label-free, selective detection of biomolecules. Both the MEMS fabrication phase and the bioactivation protocol were designed to ensure functionality of on-chip test electronic circuitry. Specifically, the bioactivation steps were performed with single drops of the reagents on the active part of the chip to minimize impact on the electronics and package. The CMOS compatibility of the final device is demonstrated by simultaneous operation of the MEMS resonator and the test electronics. The resonator mass sensitivity, determined by resonator loading with gold nanoparticles, compares favorably with those of QCMs and other MEMS resonant mass sensors. To validate the device operation as a biosensor, synthetic oligonucleotide sequences designed to bind to a specific human mRNA (involved in the synthesis of human methylguanine-DNA methyltransferase, a DNA repair protein) were used as probes and covalently bound to the resonator surface. The resonance frequency shift of different sensors at the same concentration of the analyte confirms the inverse dependence of the sensitivity on the mass of the resonator. © 2014 Springer International Publishing Switzerland