This paper reports a novel biosensor monolithically integrate optical waveguide into PDMS microcantilever. The sensor
consists of buried optical fibers, integrated optical waveguide and horizontal PDMS microcantilever suspended into
microfluidic channel. The thin PDMS layer involves microcantilever, microfluidic cannels and optical channels
fabricated using soft lithography technique. The thin layer is covered by semi-bonding of a glass slide and a PDMS layer
to enable introducing the material of waveguide core into the waveguide channel embedded into PDMS microcantilever.
The covering layers are then replaced by other PDMS layers which have hollow features to release the microcantilever
for free deflection and to seal microfluidic network. The input and output multimode fibers are horizontally inserted into
the optical channels. The light received at the input fiber is conducted through the optical waveguide microcantilever and
is delivered to the output fiber. Numerical model is presented to simulate the optical performance of the optical
waveguide PDMS microcantilever under fluid flow testing and to find the proper dimensions and waveguide material.
The deflection of microcantilever under flow loading distorts the light and causes power loss at the output fiber.
COMSOL Multiphysics 3.5 is used to perform fluid structure interaction analysis to assess the cantilever defection due
to fluid flow and the optical simulation to estimate the power loss due to cantilever deflection. The proposed biosensor
can be used to measure the force within the range of living cell growth force and to be integrated within bio-sensing
microdevices to carefully measure the fluid flow rate.
In this paper, a fully integrated flow sensor is designed and simulated. The sensor involves three PDMS layers,
monolithic integration of microfluidic channels and detection unit. The middle thin layer includes the PDMS
microcantilever and the microchannels network. The thin layer is sandwiched between the bottom and top PDMS layers
to provide microfluidic environment and to release the cantilever for deflecting. The pressure difference on the cantilever
causes the cantilever deflection. The optical fibers are embedded in the optical channels to send the light to the gold
deposited cantilever tip and to detect the reflected light. Finite element analysis is done using COMSOL Multiphysics
3.5. Fluid structure interaction is done on the cantilever to find the cantilever defection in response to fluid flow in the
microchannels. Optical power loss due to cantilever deflection is simulated by two integrated optical fibers. The
numerical results confirm the feasibility of detecting the PDMS cantilever deflection in the range of regular microfluidic