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This study presents the design of thermocouples to enhance the detectivity of thermoelectric (TE) infrared (IR) sensor. The IR sensor is implemented using the standard TSMC CMOS processes. Merits of the design include: (1) to enlarge the width of thermocouple to minimize the influence of thermal noise, (2) no need to change the existing structure design. The proposed design is shown in Fig. 1. The IR sensor with higher detectivity (which means its easier for signal processing) is a design target. Measurement results demonstrate the proposed IR sensor can achieve 21.7% detectivity improvement and sustain the responsivity within 8.4% decrease in total. It indicates that this simple approach can successfully enhance the total performance of TE IR sensor.

This paper presents the design and fabrication of a single-layer out-of-plane thermal actuator. The step-bridge structure design enables bending and then buckling of the actuator in the out-of-plane direction by Joule heating. Moreover, the moving direction of the actuator can be specified by the step structure. In summary, the step-bridge actuator design has the following five merits: (1) The load-deflection relation is easily tuned; (2) the bistable buckling behavior is prevented; (3) the unwanted vibration modes can be suppressed; (4) the delamination problem is prevented; and (5) the bridge structure is stiffer and more stable. The actuator and its application on a lens positioning stage have been implemented using p++ Si layer by bulk micromachining. It demonstrates that a typical actuator would move upward with an amplitude near 13 mum when driven at 54 mW.

An innovative process to integrate microneedle and CNT nanofilter is developed to realize a selective transdermal drug delivery. The microneedle is fabricated with SU-8 by double drawing lithography process. These microneedles are strong enough to penetrate skin easily and deliver drugs to the tissues under it. The CNT bundles integrated within microneedles could act as nanofilters to block all the micro-scale substance and selectively deliver drugs. Two kinds of biomolecules, glucose and Hemagglutinin, are used for tests. Glucose, whose dimension is much smaller than the inner diameter of the CNT hollow channel, could pass the CNT nanofilter just by applying pressure. The transport rate is proportional to the pressure applied. Hemagglutinin, which is a kind of cylindrical molecules whose dimension is close to the inner diameter of the CNT hollow channels, cannot pass through the CNT nanofilter just by applying pressure. In our previous study, we already confirmed that only when both electric field and pressure are applied together, hemagglutinin could be aligned by DEP force then pass through the CNT nanofilter. When glucose and hemagglutinin are mixed together, the delivery of hemagglutinin could be controlled by electric field when the glucose is always delivered by applying pressure.

This study reports the design architecture to embed piezoresistive pressure sensor into accelerometer (PinG sensor) on a single chip by using the cavity-SOI process. The monolithic sensing chip can find various applications such as tire pressure monitoring system (TPMS), etc. The merits of the presented design includes significant chip size reduction by integrating the diaphragm of pressure sensor into the proof-mass of accelerometer, as well as better manufacturability through combining piezoresistor (PZR) process and CSOI process. Preliminary tests demonstrated the feasibility of detecting both pressure and acceleration using the presented PinG sensor. This design architecture is also applicable for other sensors integration.

We propose a forming method of hydrogel-based cell sheets for regenerating three dimensional lobule-mimetic constructions. Accumulating the cells are conventional methods of three dimensional designs. In this study, we have designed a cell sheet chip to form a poly (ethylene glycol) diacrylate (PEGDA)-based cell sheet by two methods. First method is to pattern cells by DEP force for mimicking the pattern of the hepatocyte in vivo. Second method is to embed cells by UV light for photopolymerizing the PEGDA-based cell sheet. Stacking chip was used to form multilayer PEGDA-based cell sheets. The three dimensional lobule-mimetic regeneration will have widespread the applications in tissue engineering and detoxication experiments.

This study exploits a novel two-stage solidification technology to realize anisotropic magnetic polymer composites (MPC, polymer with magnetic powders). The merits of the presented process technology are as follows: (1) magnetic strength of MPC is controlled by weight fraction of magnetic powder, (2) volume of liquid MPC is controlled by pneumatic system, (3) surface of liquid MPC is solidified by UV, and (4) magnetization and solidification of MPC inside the solidified surface. In applications, the polymer-NdFeB composites magnetic structures are realized respectively in liquid and air medium, and further integrate with MEMS structures. The discrete NiFeB-MPC balls (Diameter:500μm-3200μm) with anisotropic magnetization are achieved. Performances enhancement of NiFeB-MPC (30wt%) by anisotropic magnetization during two-stage solidification are: coercivity force (356%), remanence (61%), and saturation magnetization (75%). Assembly of MPC on MEMS structures and the following driving tests are also demonstrated.

This study presents a novel approach to fabricate highly-structured 3D vertically-aligned carbon nanotubes (VA-CNTs) architectures, and further integrates 3D VA-CNTs with MEMS surface micromachining to fabricate suspended 3D CNTs structures. The merits of presented approach are as follows: (1) highly-structured 3D VA-CNTs stacks can be achieved by predefining multilayered Al/Fe catalyst films; (2) only single run of the pyrolysis CVD process is required to grow multilayered 3D VA-CNTs stacks; (3) the design flexibility of the microstructure in out-of-plane direction can be increased by the variation layers of CNTs stacks. Preliminary fabrication results implement various 3D VA-CNTs architectures. Furthermore, 3D CNTs stacks have been integrated with MEMS surface micromachining to demonstrate different thickness of 3D CNTs suspended cantilevers and probe. The out-of-plane resonant frequency has also been calibrated to characterize different stiffness of the 3D CNTs suspended devices.

A stress isolation guard-ring to reduce the unwanted signals induced by the environmental disturbances for a packaged three-axis piezoresistive accelerometer is proposed [1–2]. This study further reports an optimum design to shrink the size of guard-ring, yet maintain the performance of accelerometer. The commercial finite element analysis (FEA) software, CoventorWare, is employed to evaluate the candidate designs of sensors. The Taguchi's optimum design method is further employed to improve the sensor performances under environment disturbances and to shrink the size of the stress isolation structure. Based on the results, the performance of the accelerometer is improved both in offset shift and sensitivity shift for one order of magnitude, and the size of the stress isolation structure (the sum of guard-ring length/width and connection bridge length) has been shrunk for 29% (from 138 μm to 98 μm). Moreover, the unwanted higher vibration modes are far away from the first three modes. The proposed accelerometer design keeps the advantages of the original three-axis accelerometer design.

In this study, a novel piezoresistor (PZR) design to improve the sensitivity of the piezoresistive type pressure sensor is reported. In this design, the PZR combined with various doping concentrations and doping depths is proposed and implemented. According to the design concept, the combined PZR which includes multiple piezoresistance coefficients would be arranged in a unique shape, just like a ladder. Theoretically, the sensitivity improvement could boost up to 15% based on this PZR design, even under the conditions of membrane edge offset due to fabrication processes. As a result, the sensitivity of the pressure sensor which adopted the Ladder shape PZR design is 0.058 mV/V/kPa. Moreover, the doping profile of the Ladder shape PZR is also extracted by SIMS. The serial measurements successfully prove the feasibility of this design concept. In the future, the presented PZR design can be further extended to various piezoresistive sensors, such as accelerometer, gyro, etc.

This study reports the performance of a three-axis piezoresisitvie accelerometer with a guard-ring structure after plastic packaging. The accelerometers, with and without guard-ring structure, are capped with glass substrate to form the glass/Si/glass sandwich and then encapsulated in plastic package. The testing results on these packaged accelerometers have shown that the guard-ring structure successfully suppresses the performance shift caused by plastic package for one order of magnitude. The glass/Si/glass sandwich structure adds air damping to the accelerometer, hence its resonant frequency is slightly reduced (less than 0.5%). Moreover, the guard-ring structure has relatively large stiffness and is considered as a rigid body, and its influence on the sensor dynamics can be ignored. In conclusion, the guard ring structure significantly reduces the performances variation of packaged sensor. Thus, the inexpensive plastic encapsulated package for accelerometers can be implemented on the real products.

This study designs and implements a stress isolation guard-ring structure to improve the performances of the existing single proof-mass 3-axis piezoresistive accelerometer. Thus, the environment disturbances (temperature variation and force/deflection transmittance) for such packaged 3-axis piezoresistive accelerometer are significantly reduced. Measurements demonstrate the guard-ring design successfully reduce the false signals (induced by temperature variation and force/displacement transmittance) for one order of magnitude. Moreover, the proposed accelerometer still maintains the advantages of existing design, such as single proof-mass for 3-axis acceleration sensing, and better linearity. Sensitivities of present accelerometer range 0.127∼1.77mV/G/V and non-linearity

This study reports a novel approach to implement the CNTs (carbon nanotubes)-based flexible capacitive strain sensor and the detection of bending strain is demonstrated. The merits of presented design are as follows, (1) employ the aligned CNTs (50µm∼100µm in height) as interdigital finger electrodes to increase sensing area and initial capacitance, (2) the 3D CNTs electrodes and electrical routings, and flexible polymer substrate are batch fabricated on Si substrate and polymer molding, and (3) the CNTs-polymer composites as sensing electrodes and electrical routing can avoid the problem of delamination. Preliminary fabrication results demonstrate a flexible capacitive sensor with 50 µm high CNTs interdigital electrodes on PDMS, the tests show its typical capacitance change is several dozens of fF and the gauge factor ranges 4.6∼6.5.

A flexible, highly-sensitive, and easily fabricated carbon nanotubes (CNTs) tactile sensor is reported in this paper. CNTs are grown and patterned on bulk-micromachined silicon substrate with 3-dimensional surface profile. After polymer molding, the CNTs with 3-dimensional distribution are successfully transferred onto a flexible PDMS with 3-dimensional tactile-bump. Advantages of presented tactile sensor are (1) exactly determine loading force by resistance change due to almost linearly current-voltage (I–V) characteristics, (2) embedded patterned CNTs into polymer using simple silicon-substrate molding process, (3) 3-dimensional distributed CNTs enable the detection of shear and normal forces, and (4) 3-dimensional polymer structure by molding as a tactile-bump. One of anisotropic-type patterned CNT approach behaves good sensing sensitivity of both normal (23%/N) and shear (18%/N) forces loading. With proper CNTs designs, tactile sensor has normal and shear forces sensitivities of up to 23%/N and 95%/N, respectively.

This study reports an easy approach to realize the flexible sensor array. The silicon-based sensor chip is discretized into small chip array. The rigid but small silicon-based pressure sensors and flexible polymer material are integrated to implement the flexible tactile sensor array. The electrical routings for sensing signals are achieved using the through-silicon interconnects and electroplated metal wires on polymer. The measurement results show that the sensitivity of tactile sensor can be up to 0.122 mV/V/kpa and the nonlinearity is about 1.7%. The bending test shows that the flexible sensor has a radius of curvature of 5.2mm. This study has successfully embedded the flexible sensor in the shoe pad to demonstrated the feasibility of wearable smart device.

This study reports a systematic approach to achieve optimal design of a piezoresistive sensor under the limitation of fabrication capabilities. The commercial finite element analysis (FEA) software, CoventorWare, is employed to evaluate the candidate designs of a piezoresistive pressure sensor. The Taguchi's robust design method is further employed to consider the deviation from manufacturing (e.g. dimensions, alignment, etc.). The full scale span (sensitivity) of the sensors was chosen as quality characteristics. The effects of manufacturing related restrictions were estimated by the noise factor analysis. Then, the optimal design of a sensor, which realizes the optimization of sensor signal output and minimization the influence of the variation of the design factors, is achieved through thoughtful considerations and arrangements. In application, the micro pressure sensor is design and fabricated, and the full scale span of sensor has been improved for 20% (from 78.3mV to 94mV).

This study reports a simple approach to implement a flexible CNTs tactile sensor to enable the detecting of normal and shear forces. The merits of the presented tactile sensors are as follows, (1) embedded patterned CNTs into polymer using simple Si-substrate molding process, (2) 3D distributed CNTs enable the detection of shear and normal forces, and (3) 3D polymer structure by molding as a tactile-bump. In applications, the CNTs are grown and patterned on bulk-micromachined Si substrate with 3D surface profile. After polymer molding, the 3D distributed CNTs are successfully transferred onto a flexible PDMS with 3D tactile-bump. With proper CNTs pattern designs, the tactile sensor has a sensitivity (linearity) of up to 20.95%/N (R2=0.93) for normal load, and up to 95.24%/N (R2=0.95) for shear load.

This study presents the design and fabrication of a single-layer out-of-plane thermal actuator. The step-bridge structure design enables the actuator bent and then buckled in the out-of-plane direction by Joule-heating. In summary, the step-bridge actuator design has five merits: (l)The linear load-deflect ion relation is achieved, (2)The bi-stable buckling behavior is prevented, (3)The unwanted vibration modes can be suppressed, (4)The delamination problem is prevented, and (5)The bridge structure is stiffer and more stable. The actuator and its application on a lens positioning stage have been implemented using p++ Si layer by bulk micromachining.

This study reports a novel approach to the implementation of 3D carbon nanotube (CNT) interdigitated finger electrodes on flexible polymer, and the detection of strain, bending curvature, tactile force and proximity distance are demonstrated. The merits of the presented CNT-based flexible sensor are as follows: (1) the silicon substrate is patterned to enable the formation of 3D vertically aligned CNTs on the substrate surface; (2) polymer molding on the silicon substrate with 3D CNTs is further employed to transfer the 3D CNTs to the flexible polymer substrate; (3) the CNT-polymer composite (~70 μm in height) is employed to form interdigitated finger electrodes to increase the sensing area and initial capacitance; (4) other structures such as electrical routings, resistors and mechanical supporters are also available using the CNT-polymer composite. The preliminary fabrication results demonstrate a flexible capacitive sensor with 50 μm high CNT interdigitated electrodes on a poly-dimethylsiloxane substrate. The tests show that the typical capacitance change is several dozens of fF and the gauge factor is in the range of 3.44-4.88 for strain and bending curvature measurement; the sensitivity of the tactile sensor is 1.11% N(-1); a proximity distance near 2 mm away from the sensor can be detected.

A unique process which utilizes membrane based vertically grown carbon nanotubes (CNTs) as nanofilters for a mass transport study is presented here. By using ions, ss-DNA and haemagglutinin as testing molecules of different dimensions, the mass transport function of the CNT membrane is investigated under pressure difference and/or electric field.

This study reports an improved approach to implement a carbon nanotube (CNT)-based flexible tactile sensor, which is integrated with a flexible print circuit (FPC) connector and is capable of detecting normal and shear forces. The merits of the presented tactile sensor by the integration process are as follows: (1) 3D polymer tactile bump structures are naturally formed by the use of an anisotropically etched silicon mold; (2) planar and 3D distributed CNTs are adopted as piezoresistive sensing elements to enable the detection of shear and normal forces; (3) the processes of patterning CNTs and metal routing can be easily batch fabricated on rigid silicon instead of flexible polymer; (4) robust electrical routing is realized using parylene encapsulation to avoid delamination; (5) patterned CNTs, electrical routing and FPC connector are integrated and transferred to a polydimethylsiloxane (PDMS) substrate by a molding process. In application, the CNT-based flexible tactile sensor and its integration with the FPC connector are implemented. Preliminary tests show the feasibility of detecting both normal and shear forces using the presented flexible sensor.

This study designs and implements a stress isolation guard-ring structure to improve the performances of the existing single proof-mass three-axis piezoresistive accelerometer. Thus, the environment disturbances, such as temperature variation and force/deflection transmittance, for a packaged three-axis piezoresistive accelerometer are significantly reduced. In application, the three-axis piezoresistive accelerometer has been fabricated using the bulk micromachining process on the SOI wafer. Experimental results show that the out-of-plane deformation of the suspended spring mass on the packaged accelerometer is reduced from 0.72 to 0.10 µm at a 150 °C temperature elevation. The temperature coefficient of zero-g offset for the presented sensor is reduced, and the temperature-induced sensitivity variation is minimized as well. Measurements also demonstrate that the guard-ring design successfully reduces the false signals induced by the force and displacement transmittance disturbances for one order of magnitude. Moreover, the three-axis acceleration sensing for the presented accelerometer with guard ring has also been demonstrated with sensitivities of 0.12–0.17 mV V−1 g−1 and nonlinearity < 1.02%.