Home Research Focus Publications 2007 – 1999 - 2006 Personnel Activities	Research Focus The biosensors laboratory focuses on development of wireless implantable sensors for human physiological measurements. Current research interests include the magnetic harmonic sensors, the inductor-capacitor resonant-circuit (LC) sensors, and the magnetoelastic sensors. This laboratory also collaborates with Engineered Biomaterials Laboratory to develop a magnetoelastic vibrational coating for suppressing biofouling and controlling cell proliferation. This laboratory is equipped with standard device fabrication instruments such as circuit fabrication station, as well as device characterization equipments such as high-frequency spectrum/network analyzers, waveform generators, and various amplifiers and filters. This lab is also capable of rapid prototyping with equipments such as a CNC milling machine, a 3D printer, and a 3D scanner. This lab also has standard chemistry equipments for sensor functionalization.
	Magneto Harmonic Shift Sensors The magneto harmonic shift (MHS) sensors are based on two adjacently placed ferromagnetic strips: one magnetically soft and the other magnetically hard. When the separation distance between these two strips varies, the magnetic signature from the soft magnetic strip changes, allowing wireless detection of the sensor response by measuring the change in induced magnetic field.
		Pressure monitoring in abdominal aortic aneurysm sac The implantable pressure sensor is designed for monitoring pressure inside an abdominal aortic aneurysm sac. Changes in ambient pressure deflect the membranes, thus changing the separation distance between the biasing element (hard magnetic strip) and sensing element (soft magnetic strip). This alters the sensor signature allowing remote pressure monitoring by measuring the changes in magnetic field.
	Magnetoelastic Harmonic Sensors This wireless force mapping sensor system is designed for real-time monitoring of compressive forces on knee implants. Since magnetoelastic material changes its magnetization property with the applied force, an array of magnetoelastic strips, detected via a set of detection coils, can be used to map the surface profile on a knee implant (the PE insert) wirelessly.
	Inductor Capacitor Resonant Circuit Sensors The LC sensor is made of a planar inductor and capacitor printed on a substrate. To monitor parameters of interest, the sensor is embedded inside the test medium and its response is remotely detected through a coil connected to a sensor reader. Parameters such as humidity and various gases are detected by applying a chemically responsive coating on the capacitor. As the target parameter changes, the coating changes the capacitor’s capacitance and this leads to changes in the sensor’s resonant frequency. The biosensors laboratory is currently applying this sensor technology for monitoring food quality and humidity inside civil infrastructures. A wound healing monitoring sensor is also being fabricated based on the LC sensor technology.
	Various designs of the inductor-capacitor resonant circuit sensors
	Magnetoelastic Sensors Another focus of this lab is the development of a disposable sensor for rapid microbial detection. Potential applications include controlling of food quality and safety (E. coli) as well as monitoring nosocomial infections (MRSA). The sensor is based on an array of magnetically interrogated, vibrating magnetoelastic sensors functionalized with proteins, antibodies and/or phages. Bacteria detection is realized by tracking the change in the resonance frequency and/or amplitude of the sensor, which is caused by the mass increase when the bacteria bind to the functional coating. The strength of the bonds is also measured by linearly increasing the sensor vibration until a bond-breaking event is observed. Specific bacteria identification is achieved by analyzing the bond strengths between the target bacteria and the sensor array.
	(Left) Target analytes attached to the sensor. (Right) Sensor vibration removes non-binding analytes from its surface.
	Magnetoelastic Vibrational Coating In collaboration with the Engineered Biomaterials Lab, we are developing a remotely controlled antifouling coating for reducing biofilm growth on biomedical implants. The coating is based on a magnetoelastic layer that vibrates in the presence of a magnetic AC field. Through an adjacently located device that generates controllable magnetic fields, the coating can be set to vibrate at a predetermined amplitude and frequency as a means for biofilm growth management. The novelty of this technology is that the coating characteristic can be remotely altered after deployment in vivo through changing magnetic field strength. In addition, it is also possible to monitor biofilm growth on the coating in vivo by measuring the changes in the magnetic field signature from the coating (coating vibration generates a secondary magnetic flux that can be independently monitored). The ability to measure biofilm growth and adjust the coating characteristic in vivo allows the creation of a smart antifouling coating that can precisely control biofilm formation by activating the vibration only when it is needed.