Abstract
We present a wearable microfluidic impedance cytometer implemented on a flexible circuit wristband with on-line smartphone readout for portable biomarker counting and analysis. The platform contains a standard polydimethylsiloxane (PDMS) microfluidic channel integrated on a wristband, and the circuitry on the wristband is composed of a custom analog lock-in amplification system, a microcontroller with an 8-bit analog-to-digital converter (ADC), and a Bluetooth module wirelessly paired with a smartphone. The lock-in amplification (LIA) system is implemented with a novel architecture which consists of the lock-in amplifier followed by a high-pass filter stage with DC offset subtraction, and a post-subtraction high gain stage enabling detection of particles as small as 2.8 μm using the 8-bit ADC. The Android smartphone application was used to initiate the system and for offline data-plotting and peak counting, and supports online data readout, analysis, and file management. The data is exportable to researchers and medical professionals for in-depth analysis and remote health monitoring. The system, including the microfluidic sensor, microcontroller, and Bluetooth module all fit on the wristband with a footprint of less than 80 cm2. We demonstrate the ability of the system to obtain generalized blood cell counts; however the system can be applied to a wide variety of biomarkers by interchanging the standard microfluidic channel with microfluidic channels designed for biomarker isolation.
Highlights
Capable smartphones and cheaper off-theshelf components are constantly pushing what technology can achieve on-the-go[1]
We present a portable and fully integrated system including an lock-in amplification (LIA), a microfluidic polydimethylsiloxane (PDMS) biosensor, a microcontroller, and a Bluetooth module all compacted onto a flexible circuit board in the form of a low-profile wristband with live smartphone readout through an Android application
The biosensor used in this work relies on an electric field generated between two electrodes within a microfluidic channel, with the baseline impedance representing phosphate buffered solution (PBS), and variable impedance resulting from particle flow through the electric field
Summary
Capable smartphones and cheaper off-theshelf components are constantly pushing what technology can achieve on-the-go[1]. Robust and powerful electronics are driving progress for medical devices, which can be chronically worn or implanted. With current capabilities of digital technology, data sharing, and cloud processing, scientists envision a virtual medical system for providing continuous patient-centered care remotely. There are tight budget constraints and medical criteria, which biomedical devices must be approved for by the FDA to enter the market when considering wearability or implantability, such as weight and size, biocompatibility, aesthetic factors, and power consumption[3]. The market for wearable devices has been rapidly growing due to recent achievements in developing miniaturized sensors[4]. Due to the development of incredibly robust and miniature accelerometers with microscale processing, devices such as the Fitbit have entered today’s market for monitoring heart rate and user exercise activity[5]. A variety of flexible electronics are currently being developed by researchers to monitor perspiration for glucose levels and other
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