In this paper we present the novel compact structure of a multimode interference (MMI) based biosensor. We analyze its working principle, evaluate its expected measurement errors and discuss some possible techniques to reduce them. A full description of phase-error (PE) and cross-talk (CT) for the MMI based biosensor is done. Through simulations we have analyzed the windowing technique and the effect of CCD camera resolution in the reduction of PE and CT. We show that the windowing technique is very effective in reducing PE and CT, where the best results are achieved for the Blackman window with an average improvement coefficient of 1210. The reduction of spectral leakage from this window, due to the high roll-off rate of its side lobs, is dominant against the worse spectral resolution that this window has compared to the others. Increasing the CCD camera resolution from 6 × 103 pixels/m to 18 × 103 pixels/m is associated by a rapid reduction of PE and CT with an average improvement coefficient of 44.4. A further increase in the camera resolution is not necessary as it would increase the cost of the device with a very low profit in measurement accuracy.
We propose the novel structure of an interferometric biosensor based on multimode interference (MMI) waveguides. We present the design of the biosensor using eigenmode expansion (EME) method in accordance with the requirements and standards of today's photonic technology. The MMI structures with a 90 nm Si3N4 core are used as power splitters with 5 outputs. The 5 high-resolution images at the end of the multimode region show high power balance. We analyze the coupling efficiency of the laser source with the structure, the excess loss and power imbalance for different compact MMI waveguides with widths ranging from 45 μm to 15 μm. For a laser source with a tolerance of ±1mm in linearization we could achieve a coupling efficiency of 52%. MMI waveguides with tapered channels show excess loss values under 0.5 dB and power imbalance values under 0.08 dB. In addition, we show that for a 10 nm deviation of the source wavelength from its optimal value and for a 10 μm deviation of the MMI length from its optimal value, the performance of the MMI waveguides remains acceptable. Finally, we analyze the power budget of the whole biosensor structure and show that it is sufficient for the proper operation of this device.
Future viral outbreaks are a major threat to societal and economic development throughout the world. A rapid, sensitive,
and easy-to-use test for viral infections is essential to prevent and to control such viral pandemics. Furthermore, a
compact, portable device is potentially very useful in remote or developing regions without easy access to sophisticated
laboratory facilities. We have developed a rapid, ultrasensitive sensor that could be used in a handheld device to detect
various viruses and measure their concentration. The essential innovation in this technique is the combination of an
integrated optical interferometric sensor with antibody-antigen recognition approaches to yield a very sensitive, very
rapid test for virus detection. The sensor is able to spot the herpes virus at concentrations of just 850 particles per
milliliter under physiological conditions. The sensitivity of the sensor approaches detection of a single virus particle,
yielding a sensor of unprecedented sensitivity with wide applications for viral diagnostics. The sensor's detection
principle can be extended to any biological target such as bacteria, cells and proteins and for which there are specific
antibodies. The nature of the sensor enables multiplexed detection of several analytes at the same time.
Conference Committee Involvement (6)
Advances in Global Health through Sensing Technologies 2015
20 April 2015 | Baltimore, MD, United States
Sensing Technologies for Global Health, Military Medicine, and Environmental Monitoring IV
5 May 2014 | Baltimore, MD, United States
Sensing Technologies for Global Health, Military Medicine, and Environmental Monitoring III
29 April 2013 | Baltimore, Maryland, United States
Sensing Technologies for Global Health, Military Medicine, Disaster Response, and Environmental Monitoring II
23 April 2012 | Baltimore, Maryland, United States
Sensing Technologies for Global Health, Military Medicine, Disaster Response, and Environmental Monitoring
25 April 2011 | Orlando, Florida, United States
Sensors, and Command, Control, Communications, and Intelligence (C3I) Technologies for Homeland Security and Homeland Defense IX
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