Wirelessly interrogated bio-MEMS devices are becoming more popular due to many challenges, such as improving
the diagnosis, monitoring, and patient wellbeing. The authors present here a passive, low power and small area
device, which can be interrogated wirelessly using a uniquely coded signal for a secure and reliable operation.
The proposed new approach relies on converting the interrogating coded signal to surface acoustic wave that is
then correlated with an embedded code. The suggested method is implemented to operate a micropump, which
consist of a specially designed corrugated microdiaphragm to modulate the fluid flow in microchannels. Finite
Element Analysis of the micropump operation is presented and a performance was analysed. Design parameters
of the diaphragm design were finetuned for optimal performance and different polymer based materials were used
in various parts of the micropump to allow for better flexibility and high reliability.
Proc. SPIE. 6928, Active and Passive Smart Structures and Integrated Systems 2008
KEYWORDS: Microelectromechanical systems, Microfluidics, Manufacturing, Control systems, Finite element methods, Microfabrication, Electronics engineering, Acoustics, System integration, Radio propagation
Micro-fabricated diaphragms can be used to provide pumping action in microvalve and microfluidic applications.
In this paper, a design for a micro-diaphragm that features low power and small area is presented. The diaphragm
is actuated using a Surface Acoustic Wave (SAW) device that is interrogated from an RF signal to provide secure
actuation operation. The micropump is targeted for in vivo nano-scale drug delivery and similar applications.
For low power micropump operation, it is important to design the diaphragm with a higher flexibility while
maintaining the stability. Analysis is carried out using ANSYS simulation tools with different design methods
and materials. Results achieved from analytical and Finite Element Modeling (FEM) methods are compared
and discussed to decide on optimal dimensions for the diaphragm.
There are vast advantages of using a SAW device based micro-valve in Micro Electro Mechanical Systems (MEMS) and Nano Electro Mechanical Systems (NEMS) such as secure, reliable and low power operation, small size, simplicity in construction and cost effectiveness. In this paper, a Surface Acoustic Wave (SAW) based microvalve that generates micro actuations for micro-fluidic and similar applications is presented. The microvalve is batteryless and can be actuated wirelessly. The security of the device is enhanced by using a coded SAW correlator that is integrated as part of the microvalve. A theoretical analysis of how the actuation mechanism operates is carried out and simulation results of the new micro-valve structure are discussed. ANSYS simulation tool is used to design and simulate the micro-valve structure. Characteristics of the microvalve actuator in terms of displacement for different operating conditions are also discussed.
In this paper we propose the use of a RF controlled microvalve for implementation on a PZT substrate for biomedical
applications. Such device has a huge range of applications such as parallel mixing of photo-lithographically defined
nanolitre volumes, flow control in pneumatically driven microfluidic systems and lab-on-chip applications. The
microvalve makes use of direct actuation mechanisms at the microscale level to allow its use in vivo applications. A
number of acoustic propagation modes are investigated and their suitability for biomedical applications, in terms of the
required displacement, device size and operation frequency. A theoretical model of the Surface Acoustic Wave (SAW)
device is presented and its use in micro-valve application was evaluated using ANSYS tools. Furthermore, the wireless
aspect of the device is considered through combining the RF antenna with the microvalve simulation by assuming a high
carrier frequency with a small peak-to-peak signal. A new microvalve structure which uses a parallel type piezoelectric
bimorph actuator was designed and simulated using ANSYS tools. Then, further optimization of the device was carried
out to achieve a better coupling between electrical signal and mechanical actuation within the SAW device.