Wen Zhiyu

A novel remote controlled capsule for site-specific drug delivery in human GI tract

Remote controlled capsule (RCC) has been extensively used in the field of site-specific drug delivery. It is a potent tool to study the regional drug absorption of the gastrointestinal (GI) tract that provides pharmaceutical scientists with significant pharmacokinetics data for oral drug formulation development. In present investigations, a patented novel RCC has been devised based on micro-electronic mechanical system (MEMS) technology. Micro-thrusters were for the first time exploited as drug release actuators of RCCs. As the micro-thruster is ignited by a radio frequency (RF) signal, the thrust force generated by the propellants pushes the piston forward and leads to a rapid and complete expulsion of therapeutic agents from the capsule. The micro-thruster merely consumes 120 mW for ignition and the duration time of drug release is decreased to less than 1 s. The feasibility of the novel RCC was evaluated through animal experiments in beagles using aminophylline as the model drug. The novel RCC developed is a promising alternative for site-specific drug delivery in human GI tract.

Vibration-based Piezoelectric Generator and Its Application in the Wireless Sensor Node

The mathematical model of the vibration-based piezoelectric generator with the proof mass supported by a cantilever is established.The formulas of the frequency,the output voltage and the output power are derived.Testing results show that this model is more accurate than Roundys model.According to such characters as large transient power and small average power of the typical wireless sensor node,the power self-regulation circuit of the piezoelectric multi-shaker micro-generator is proposed.When the electricity in the super capacitor of the main circuit is enough to power the wireless sensor node,the main circuit is opened by the ancillary return circuit and the node starts to measure and transfer the results to the monitoring center.The field test on an engine of a ship shows that the vibration-based piezoelectric generator can be used to power a wireless sensor node.

The fabrication of vibration energy harvester arrays based on AlN piezoelectric film

The fabrication and measurement results of the vibration energy harvester arrays based on the piezoelectric aluminum nitride (AlN) film are presented. The structure design and fabrication process of the device are introduced. The key material, the AlN film with crystal orientation (002), was deposited by pulsed-DC magnetron sputtering and characterized by X-ray diffraction (XRD). The resonant frequency, power out, and the open circuit voltage of the device are detected. The optimized load of 80 kΩ and a remarkable maximum power out of 30.4 μW are obtained when the acceleration of 0.9g (g is standard gravity acceleration) is applied.

Design of site specific delivery capsule based on MEMS

Site specific delivery capsule (SSDC) is a new method to realize non-invasive drug delivery to the selected sites of the human alimentary tract. With SSDC, non-invasive regional drug absorption (RDA) studies are taken to provide the pharmacokinetics data for oral drug formulation development. In this research, a new SSDC has been developed based on MEMS technology. An innovative drug release actuator was designed with simple and reliable structure, which includes a micro-heater array, an elastomeric bellows and a piston. The power of the compressed elastomeric bellows driven the piston to expelled drug out of the capsule. Piston was adhibited to the micro-heater array by low melting point adhesive. The power consumption of the micro-heater array has been decreased to 450 mJ by MEMS technology. A magnetic marker monitoring (MMM) system was developed to monitor the location of the capsule inside the human alimentary tract by providing three- dimensional location data. We get the pharmacokinetic characteristics data of aminophylline (150 mg) in the proximal small intestine of 12 healthy volunteers with the SSDC.

Calculation of surface acoustic waves in a multilayered piezoelectric structure

The propagation properties of the surface acoustic waves (SAWs) in a ZnO-SiO2-Si multilayered piezo- electric structure are calculated by using the recursive asymptotic method. The phase velocities and the electro- mechanical coupling coefficients for the Rayleigh wave and the Love wave in the different ZnO-SiO2-Si struc- tures are calculated and analyzed. The Love mode wave is found to be predominantly generated since the c-axis of the ZnO film is generally perpendicular to the substrate. In order to prove the calculated results, a Love mode SAW device based on the ZnO-SiO2-Si multilayered structure is fabricated by micromachining, and its frequency responses are detected. The experimental results are found to be mainly consistent with the calculated ones, except for the slightly larger velocities induced by the residual stresses produced in the fabrication process of the films. The deviation of the experimental results from the calculated ones is reduced by thermal annealing.

Theoretical analysis and concept demonstration of a novel MOEMS accelerometer based on Raman—Nath diffraction

The design and simulation of a novel microoptoelectromechanical system (MOEMS) accelerometer based on Raman—Nath diffraction are presented. The device is planned to be fabricated by microelectromechanical system technology and has a different sensing principle than the other reported MOEMS accelerometers. The fundamental theories and principles of the device are discussed in detail, a 3D finite element simulation of the flexural plate wave delay line oscillator is provided, and the operation frequency around 40 MHz is calculated. Finally, a lecture experiment is performed to demonstrate the feasibility of the device. This novel accelerometer is proposed to have the advantages of high sensitivity and anti-radiation, and has great potential for various applications.

Power Self-Regulation Circuit of Piezoelectric Multi-Shaker Micro-Generator

Based on requirement for power supply of wireless emitting module of machine malfunction vibration monitoring system and characteristic of low power output of micro-generator, a novel power supply manage and control module which controls output power of micro-generator is advanced, and low power consumption self-regulation circuit is designed. Its feasibility has been proved by experiments. Under the condition of resonance frequency 50 Hz and acceleration 0. 15 g ~ 0. 2 g, piezoelectric multi-shaker micro-generator managed by power self-regulation circuit could maintain wireless emitting module of machine malfunction monitoring system to stably work for long time at 3.28 V.

Preparation and characterization of three-dimensional micro-electrode for micro-supercapacitor based on inductively coupled plasma reactive etching technology

The capacity of supercapacitor charge storage depends on the size of the electrode surface area and the active material on the electrodes. To enhance the charge storage capacity with a reduced volume, silicon is used as the electrode material, and three-dimensional electrode structure is prepared to increase the electrode surface area on the footprint area by inductively coupled plasma reactive etching (ICP) techniques. The anodic constant current deposition method is employed to deposit manganese oxide on the electrode surface as the electroactive material. For comparison, samples without slot are prepared with a two-dimensional electrode. Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) are used to characterize the surface morphology of the electrode structure and the deposited electroactive material. Electrochemical properties of the electrode are characterized by the cyclic voltammetry (CV) and the constant current charge-discharge method. Experimental results show that our approach can effectively increase the electrode surface area with more electroactive substances, and hence can increase storage capacity of the micro-supercapacitor.

Design and process test of a novel MOEMS accelerometer based on Raman—Nath diffraction

A novel micro-opto-electro-mechanical system (MOEMS) accelerometer based on Raman—Nath diffraction is presented. It mainly consists of an FPW delay line oscillator and optical strip waveguides. The fundamental theories and principles of the device are introduced briefly. A flexural plate-wave delay-line oscillator is designed to work as an acousto-optic (AO) shifter, which has a Klein—Cook parameter of 0.38. Single-mode optical strip waveguides of 2 μm in width and thicknesses of 0.6 μm are designed by using the effective index method for light transmission. The Ey00 mode waveguide polarizers are designed to ensure the consistency of the light polarization in the waveguides. The fabrication process, based on (100) oriented, 450-μm-thick silicon wafers is proposed in detail, and some difficulties in the process are discussed carefully. At last, a series of process tests are undertaken to solve the proposed problems. The results indicate that the proposed design and fabrication process of the device is dependable and realizable.