This thesis describes the development of wireless portable microfluidic biosensor systems for real-time monitoring of clinical microdialysate streams.
Zigbee and Bluetooth wireless potentiostats for controlling amperometric biosensors are designed and implemented on miniaturised battery-powered printed circuit boards (PCBs). The Zigbee and the Bluetooth potentiostats are coupled with a Python and an Android app, respectively, enabling real-time data recording and plotting. The potentiostats are validated with glucose and lactate biosensors.
A robust 3D printed microfluidic chip enabling the detection of high-temporal resolution chemical changes in a dialysate stream is developed. The device consists of a microfluidic channel with secure low-volume connections that integrates needle-based biosensors. Optimisation of fabrication of the microfluidic channel and the resulting improvement in sensor response time made it possible to resolve transient metabolite concentration changes as short as 8 s.
A glutamate biosensor that integrates into the high-time resolution microfluidic chip is developed. It is based on a combined needle electrode, coated with a hydrogel layer containing glutamate oxidase. Optimisation of the biosensor fabrication and the resulting improvement in biosensor selectivity, sensitivity and stability are shown. Typical results are a glutamate sensitivity of 1 pA/μM, a detection limit of 0.25 μM and a life-time of 50 hours in continuous operation.
An android app for the wireless control of LabSmith microfluidic instruments is developed, enabling in-flow biosensor calibration in a portable setup.
The novel wireless microfluidic biosensor systems are validated for the online monitoring of (i) traumatic brain injury (TBI) patients in the intensive care unit and (ii) transplant porcine kidneys from retrieval to reperfusion, including during transportation and during various preconditioning stages. A pathophysiological dynamic glutamate change in the human brain is reported.