Mass Response of A CMOS-Compatible, Magnetically Actuated MEMS Microbalance

In this work, the mass response of a resonant, CMOS (Complementary MOS) compatible MEMS sensor, oriented at the detection of diagnostic markers, is presented. The sensor is fabricated with a MEMS (Micro-electro-mechanical System) post-processing method on a standard, CMOS-based VLSI technology, retaining maximum compatibility with the CMOS process flow. The mechanical resonator is based on inductive actuation and detection, and the sensing is based on the microbalance principle. A protocol for covalent bonding of organo-functional silanes (to be used as link sites for biomolecular probes) on the resonator surface is presented. The effect on the mechanical frequency response of a test mass attached to the surface is demonstrated by grafting of gold nanoparticles (NPs) to the amino- terminated surface silanes. The measured mass sensitivity compares favorably both with standard Quartz Crystal Microbalances (QCM) and with existing MEMS-based approaches

The Dynamics of Quote Prices in an Artificial Financial Market with Learning Effects

In this paper we study the evolution of bid and ask prices in an electronic financial market populated by portfolio traders who optimally choose their allocation strategy on the basis of their views about market conditions. We design an order book market system where agents enter the market sequentially and trade to adjust their portfolio according to their optimal target allocations. They apply a copula function to generate the joint distribution of returns to be used to determine the optimal portfolio allocations. We create asynchronous updating assuming that different groups of agents entered the market at different moments in time. We simplify the optimization problem assuming that investors are myopic: at the beginning of the investment horizon they choose their portfolios as if there will be no further trading

Learning and the Price Dynamics of a Double-Auction Financial Market with Portfolio Traders

In this paper we study the dynamics of price adjustments in a market where portfolio traders with bounded rationality and limited resources interact through a continuous, electronic open book. The market trading activity depends on the heterogeneity of agents' beliefs. We allow agents to hold arbitrary priors about the univariate marginal distribution of returns, while we assume that agents have a constant common view of the assets' association structure. We make agents update prior marginal distributions using past realized market prices. We show that asset price dynamics is strongly affected by the structure of the learning process. Under learning the price series show long run positive trends and become non-stationary. In particular, we underline the role of the assumed assets association structure in shaping asset price dynamics

Design of an electronic oscillator for biosensing applications based on a MEMS resonator

Resonant mass sensors (i.e. microbalances) are commonly used in chemical and biochemical sensing, and their MEMS counterparts, based on MEMS resonators, are actively investigated. In this work, we present the design of an integrated electronic oscillator, based on general purpose CMOS operational amplifiers (op-amps) and conceived to operate with a magnetically actuated MEMS resonator fabricated on the same chip as the op-amps. After a description of the resonator and op-amp structure and characteristics, a two-stage, positive feedback oscillator topology is presented. The simulated behavior of the oscillator is presented and discussed, and the temperature stability of the oscillator output frequency is analyzed

Design of an Electronic Oscillator Based on an On-Chip MEMS Resonator Aimed at Sensing Applications

We present the design of an integrated electronic oscillator aimed at the detection of the response of an integrated MEMS resonant mass sensor. The resonator and oscillator are designed to be fabricated on a CMOS-compatible bulk micromachining technology which allows the coexistence of MEMS components and integrated circuits on the same chip. The resonator is targeted at the development of low-cost integrated smart biosensors for the detection of diagnostic markers in a POCT (point-of-care testing) context. The oscillator is based on a standard positive feedback topology, using the MEMS resonator as a two-port, frequency selective element. The main design issues are the low input impedance of the resonator and its significant attenuation. ELDO simulations of the designed circuit, based on an equivalent model of the resonator extracted from experimental data, were performed, and the results are presented and commented

Advances in the definition of a drop-based functionalization protocol for CMOS-compatible MEMS biosensors

Smart, MEMS-based biosensors are a promising new platform for the delivery of diagnostic services, but inclusion of on-chip CMOS electronics requires the definition a CMOS compatible techniques for the bio-activation of the sensor surface. In this work, a comparison between a sensor functionalization procedure by complete immersion of the sensor chip or by exposure to a single drop of the reagents (the latter approach being more compatible with the presence of on-chip CMOS components) is presented