Integration Of Microsensors Research Articles

Fully printed minimum port flexible interdigital electrode sensor arrays.

Screen-printed interdigital electrode-based flexible pressure sensor arrays play a crucial role in human-computer interaction and health monitoring due to their simplicity of fabrication. However, the long-standing challenge of how to reduce the number of electrical output ports of interdigital electrodes to facilitate integration with back-end circuits is still commonly ignored. Here, we propose a screen-printing strategy to avoid wire cross-planes for rapid fabrication of flexible pressure sensor arrays. By innovatively introducing an insulating ink to realize electrical insulation and three-dimensional interconnection of wire crossings, the improved sensor array (4 × 4) successfully reduces the number of output ports from 17 to 8. In addition, we further constructed microstructures on the laser-etched electrode surfaces and the sensitive layer, which enabled the sensor to achieve a sensitivity as high as 17 567.5 kPa-1 in the range of 0-50 kPa. Moreover, we integrated the sensors with back-end circuits for the precise detection of tactile and physiological information. This provides a reliable method for preparing high-performance flexible sensor arrays and large-scale integration of microsensors.

The Working Principles of a Multifunctional Bondline with Disbond Stopping and Health Monitoring Features for Composite Structures

In comparison to bolted joints, structural bonds are the desirable joining method for light-weight composite structures. To achieve a broad implementation of this technology in safety critical structures, the issues of structural bonds due to their complex and often unpredictable failure mechanisms have to be overcome. The proposed multifunctional bondline approach aims at solving this by adding two safety mechanisms to structural bondlines. These are a design feature for limiting damages to a certain size and a structural health monitoring system for damage detection. The key question is whether or not the implementation of both safety features without deteriorating the strength in comparison to a healthy conventional bondline is possible. In previous studies on the hybrid bondline, a design feature for damage limitations in bondlines by means of disbond stopping features was already developed. Thus, the approach to evolve the hybrid bondline to a multifunctional one is followed. A thorough analysis of the shear stress and tensile strain distribution within the hybrid bondline demonstrates the feasibility to access the status of the bondline by monitoring either of these quantities. Moreover, the results indicate that it is sufficient to place sensors within the disbond stopping feature only and not throughout the entire bondline. Based on these findings, the three main working principles of the multifunctional are stated. Finally, two initial concepts for a novel multifunctional disbond arrest feature are derived for testing the fundamental hypothesis that the integration of micro sensors into the disbond stopping feature only enables the crack arrest and the health monitoring functions, while reaching the mechanical strength of a conventional healthy epoxy bondline. This work therefore provides the fundamentals for future investigations in the scope of the multifunctional bondline.

Integration of Micro Sensors with Mobile Devices for Monitoring Vital Signs of Sleep Apnea Patients

This paper demonstrates a BSN-based portable monitor integrating micro sensors with mobile devices for monitoring and diagnosing obstructive sleep apnea syndrome (OSAS) at home. The system uses a micro hot-film flow sensor to detect respiratory flow, uses tri-axis micro accelerometer to detect body posture and motion intensity, and uses a micro photoelectric sensor to detect oxygen saturation of blood. The real-time vital signs are detected and transmitted wirelessly to a mobile device. The transmitted data are processed and analyzed in the mobile device and can be further transmitted to a remote medical center and physicians through mobile cellular networks or Internet for comprehensively analyzing, assessing, and diagnosing to the diseases.

Integration of microsensor for microsurgery robot’s end-effector

To enhance the effect of robotic microsurgery, the microsensors are integrated on the robot’s end-effector. On the basis of the requirements presented for the integration design, measuring mechanism for the robotic end trephine’s force and cutting depth are studied. Force microsensor and position microsensor are used to measure surgical information of the force and depth. Measuring mechanism was achieved by means of linear sliding bearing and differential measuring structure. The sensor data board was developed. With the power spectral estimation of sensor data, two digital filtering methods are proposed, to help eliminate the interference to the original microsensor signal. They are the filtering method of lowpass-bandstop serial structure suitable for a PC, and a shift average filtering algorithm suitable for the sensor data board, respectively. The experimental results show that the integration of microsensors for microsurgery robot’s end-effector can satisfy the design requirements, and the robotic end trephine can accurately fulfill the surgical task of corneal cutting.

Single-wafer-processed trench-sidewall integration and its application in a micro resonant detector for vacuum monitoring

A trench-sidewall technology is developed for single-wafer-based integration of micro sensors and actuators with in-plane lateral configuration. Piezoresistive sensing and electrostatic actuating elements can be integrated together onto the deep-trench sidewalls of in-plane microelectromechanical structures by sidewall boron diffusion. Adjacent sidewall elements are electrically isolated by previously formed SiO2-refilled trenches. Electric transference from the sidewall to wafer surface is performed via the overlaps between the sidewall-diffusion and previously doped p+ at wafer surface. As a versatile micro-fabrication process, the technology promises to be widely used. As a typical application, a cantilever-shaped micro resonant vacuum detector was formed with both sidewall piezoresistive sensing and electrostatic resonance-driving elements integrated. In addition to satisfactory electric principles measured to verify the trench-sidewall technology, the resonant sensor was used to detect vacuum by measuring the value change of quality factor in terms of vacuum pressure. The detector was successfully embedded into a glass-frit vacuum package to evaluate the vacuum-package performance. The packaged vacuum of near 20 mbar with satisfactory stability of two months was measured.

DEVELOPMENT OF A 2D MICROFLUIDIC OXYGENATION DEVICE

A novel microfluidic capillary structure was developed for use with photocatalytic oxygen generating thin films. The microfluidic element was fabricated by multilayer soft lithography, and consisted of stacked sets of arborizing channels capable in the current form of diffusing O2 into the flowing medium across a silicone membrane. Fluid was brought into intimate contact with the diffusing surface, facilitating rapid oxygenation in the laminar flow regime. Convective gas transport was modeled analytically and oxygen concentration measured in real-time by microfabricated luminescent O2 sensors embedded in the capillary channels. The microfluidic capillary array was iteratively designed according to physiological principles with the aim of minimizing shear stress. Oxygen sensors provided reliable and precise measurement of oxygenation over a range of flow rates. Hemolysis, as indicated by plasma free hemoglobin, varied with microchannel design. In capillary designs refined to eliminate adverse flow conditions, thrombus deposition and channel occlusion were greatly reduced. This study demonstrates two milestones in the development of the photolytic artificial lung: 1) Design, fabrication, and refinement of a viable blood-bearing microcapillary structure. 2) Integration of micro-sensors to monitor blood O2 concentration during physiological flow conditions.

Integration of microsensors in GaAs MESFET process

Piezoelectric pressure sensors and pyroelectric infrared detectors based on ZnO thin films have been integrated with GaAs metal-semiconductor field effect transistor (MESFET) amplifiers. The microsensors incorporate a 1 mu m-thick sputtered ZnO capacitor supported by a 2 mu m-thick aluminium membrane formed on a semi-insulating GaAs substrate. The piezoelectric pressure sensor of area 80*80 mu m2 exhibits 2.99 mu V mu bar-1 sensitivity at 400 Hz. The voltage response of a single infrared detector of area 80*80 mu m2 is 6.2 mV at 10 Hz and the time constant is 53 ms. Circuits using 4 mu m-gate GaAs MESFETs are fabricated using a planar, direct ion-implant process. The measured transconductance of a 4 mu m-gate GaAs MESFET is 25.6 mS. mm-1 at room temperature.