The field of cantilever-based sensing emerged in the mid-1990s and is today a well-known technology for label-free sensing which holds promise as a technique for cheap, portable, sensitive and highly parallel analysis systems. The research in sensor realization as well as sensor applications has increased significantly over the past 10 years. In this review we will present the basic modes of operation in cantilever-like micromechanical sensors and discuss optical and electrical means for signal transduction. The fundamental processes for realizing miniaturized cantilevers are described with focus on silicon- and polymer-based technologies. Examples of recent sensor applications are given covering such diverse fields as drug discovery, food diagnostics, material characterizations and explosives detection.

http://iopscience.iop.org/article/10.1088/0034-4885/74/3/036101/pdf

Cantilever-like micromechanical sensors

Lab-on-a-chip devices

In this Review, the interplay between materials and microfluidics is examined, with the discussion focused on how recent advances in materials fabrication have expanded the frontiers of microfluidic platforms and how the new microfluidic capabilities are, in turn, furthering materials design.

Interplay between materials and microfluidics

We report the successful fabrication and testing of 3D printed microfluidic devices with integrated membrane-based valves. Fabrication is performed with a low-cost commercially available stereolithographic 3D printer. Horizontal microfluidic channels with designed rectangular cross sectional dimensions as small as 350 μm wide and 250 μm tall are printed with 100% yield, as are cylindrical vertical microfluidic channels with 350 μm designed (210 μm actual) diameters. Based on our previous work [Rogers et al., Anal. Chem. 83, 6418 (2011)], we use a custom resin formulation tailored for low non-specific protein adsorption. Valves are fabricated with a membrane consisting of a single build layer. The fluid pressure required to open a closed valve is the same as the control pressure holding the valve closed. 3D printed valves are successfully demonstrated for up to 800 actuations.

/pdf/3d-printed-microfluidic-devices-with-integrated-valves-3uvp3g9m5s.pdf

3D printed microfluidic devices with integrated valves

Casimir effect on the critical pull-in gap and pull-in voltage of nanoelectromechanical switches is studied. An approximate analytical expression of the critical pull-in gap with Casimir force is presented by the perturbation theory. The corresponding pull-in parameters are computed numerically, from which one can notice the nonlinear effect of Casimir force on the pull-in parameters. The detachment length has been presented, which increases with increasing thickness of the beam.

Casimir effect on the pull-in parameters of nanometer switches. Microsys Technol

Published literature describes the deflection response of electro-thermal actuators to be linearly proportional to the input power. However, our simulation and empirical results show that the deflection response of our actuators was linearly proportional to the input voltage over a wide range of input voltages. The theoretical work outlined in this document shows how, depending on the temperature coefficient of electrical resistivity and the temperature coefficient of thermal resistivity, both behaviours are possible

Deflection response of electro-thermal actuators to voltage and power

We present two sample-in-answer-out integrated, automated, and inexpensive lab-on-a-chip systems that accept raw patient sample, perform sample preparation to extract the genetic material, and perform genetic amplification and analysis. While the first system performs genetic amplification via polymerase-chain-reaction and analysis using laserinduced-fluorescence capillary electrophoresis, the second system performs genetic amplification and analysis via realtime-polymerase-chain-reaction and melting-curve-analysis. Even though both systems include all the required functionality for complete genetic analysis starting from raw sample, the component cost for each shoe-box sized system is less than $1000. To operate these systems only a laptop computer and an external power are required.

/pdf/inexpensive-and-portable-sample-in-answer-out-genetic-3wits9j7el.pdf

Inexpensive and portable sample-in-answer-out genetic analysis systems for point of care applications

This paper derives a value for the required minimum feature spacing necessary for surface micromachined optical systems to achieve commercial viability. The poor performance of current surface micromachined optical systems, in large part, stems from the relatively large misalignment of their optical components. This paper aims to provide a closed-form solution expressing the insertion loss due to optical misalignment as a function of the minimum feature spacing. Assuming that the highest insertion loss acceptable in a commercial optical switch is 1 dB, the closed-form solution implies that the minimum feature spacing must be less then 0.37 /spl mu/m for commercial viability.

Required minimum feature spacing for commercial viability of raised surface micromachined optical systems

A method for making three-dimensional structures comprises providing a plurality of components, each of which is moveably coupled to a substrate. The components may be pivotally coupled to the substrate by one or more micromachined hinges. The components are moved using electrostatic forces which lift the components from the surface of the substrate. The components may then be moved further by providing electrostatic forces between components. Two or more components may engage with one another to provide a three-dimensional structure.

Method for assembling micro structures

In many types of thin-film deposition, film growth is conformal. The shape of a deposited layer follows the topography of the underlying wafer surface when deposition occurred. The result of any processing step therefore depends heavily on the preceding steps. Managing topography is an important part of the design process. Generally, design faults relating to topography can be classified into three categories: interference faults, structural faults, and behavioural faults.

R.W. Johnstone

Papers

Deflection response of electro-thermal actuators to voltage and power

Inexpensive and portable sample-in-answer-out genetic analysis systems for point of care applications

Required minimum feature spacing for commercial viability of raised surface micromachined optical systems

Method for assembling micro structures

Non-Ideal Processes