Cleopatra Cabuz

Factors enhancing the reliability of touch-mode electrostatic actuators

This paper discusses the failure modes frequently encountered in touch-mode electrostatic actuators (TMEA) and reports on practical ways of increasing the time to failure. Humidity is identified as the main source of anomalies in the behavior of TMEA and charge trapping in the dielectric as the main cause of stiction. A method for direct charge measurement is derived and the measurements show good agreement with the calculated data. A new driving scheme is proposed that, together with surface treatments based on self-assembled monolayer, desensitizes the actuator to environmental conditions. In this way, actuators working without failure in room air for over 40 million cycles were obtained.

Tradeoffs in MEMS materials

To control the third dimension of micro mechanical structures, new materials have to be designed. Unfortunately, increased manufacturability results generally in degraded mechanical and electrical characteristics. The paper is presenting a detailed analysis of p+ silicon as a mechanical material for microresonators and of the low temperature dielectrics used in electrostatic microactuators. All the relevant parameters of p+ silicon are experimentally determined and process recommendations allowing improved quality are formulated. Charge injection and trapping in low temperature dielectrics are analyzed and their impact on the behavior of the electrostatic actuators evaluated.

Electrical Phenomena at the Interface of Rolling-Contact, Electrostatic Actuators

We live today in a hyper-dynamic social, economical and technological environment that calls increasingly for portable and wearable systems. People want to be, at all times, informed and in control of the events affecting their lives. The cell phone, the pager, the laptop and palmtop computers or the implantable drug delivery systems and peacemakers are some of the first wearable/portable devices to be widely used. New, wearable, biological and chemical analysis systems are now being developed, and they will provide continue monitoring of the environment and/or of the individual’s health condition.

Enabling Technologies for a Personal Flow Cytometer (Part I)

The paper reports on three key technologies that have enabled the development of a wearable flow cytometer: flow sensing and control based on low-power MEMS-based sensors/actuators; microfluidic processing based on miniaturized disposable plastic cartridges; and optical detection based on arrays of solid-state lasers/detectors and integrated micro-optics. This instrument can provide early detection of viral and bacterial infections based on quick (30 seconds) measurement of lymphocyte and neutrophil counts [1]. Personnel with little or no medical training can use this low-cost, low-maintenance instrument in doctor’s offices, homes, and public/private-sector facilities. Multiparameter scattering-based or fluorescence-based cytometers can be developed based on this technology for clinical, industrial and military applications.

MEMS sensing and control : An aerospace perspective

Future advanced fixed- and rotary-wing aircraft, launch vehicles, and spacecraft will incorporate smart microsensors to monitor flight integrity and provide flight control inputs. This paper provides an overview of Honeywells MEMS technologies for aerospace applications of sensing and control. A unique second-generation polysilicon resonant microbeam sensor design is described. It incorporates a micron-level vacuum-encapsulated microbeam to optically sense aerodynamic parameters and to optically excite the sensor pick off: optically excited self-resonant microbeams form the basis for a new class of versatile, high- performance, low-cost MEMS sensors that uniquely combine silicon microfabrication technology with optoelectronic technology that can sense dynamic pressure, acceleration forces, acoustic emission, and many other aerospace parameters of interest. Honeywells recent work in MEMS tuning fork gyros for inertial sensing and a MEMS free- piston engine are also described.

Enabling Technologies for a Personal Flow Cytometer, Part II: Integrated Analysis Cartridges

A novel microcytometry system that monitors leukocyte populations to assess human pathogen exposure is being jointly developed by Micronics and Honeywell. The system contains both an instrument and a disposable card that contains complex microfluidic circuits for blood sample acquisition, reagent storage, erythrocyte lysis, cytometry, and waste storage. This talk discusses the subsystems that provide these functions and shows experimental results qualitatively describing hydrodynamic focusing and leukocyte populations.

Tradeoffs in micro-opto-electro-mechanical system materials

To build three-dimensional micro-opto-electro-mechanical systems (MOEMS), new materials have to be designed. However, increased manufacturability results generally in modified/degraded optical, mechanical, and electrical characteristics. The paper presents a detailed analysis of p + silicon as an opto-electro-mechanical material for microresonators, and gives some hints on the problems associated with the use of low-temperature dielectric in electrostatic microactuators. All the relevant parameters of p + silicon are experimentally determined and process recommendations allowing improved quality are formulated. Charge injection and trapping in low-temperature dielectric are analyzed and their impact on the behavior of the electrostatic actuators evaluated.