Systems-level designs of portable microfluidic cytometers for operation in the field

Abstract

small sampling volumes, minimal hydrodynamic focusing avoiding need for most sheath fluid for higher sample throughput, weight/power requirements using super-bright LEDs light sources, “top-hat” focusing optics minimizing cell-positioning requirements, small silicon photomultiplier sensors, with tightly-integrated electronics, all battery-powered and light-weight for portability. Smartphone technology includes CPU, touch-screen, digital speech recognition interface, telecommunications via phone and/or internet, GPS chip to mark the location of the patient using Motorola’s Moto Z3 Play, modular/open-architecture smartphone. The device is software-configurable from a Linux workstation running Android Studio IDE with Java and Python programming. Portable microfluidic-cytometry devices for measurements in the field requires a serious overall systems-level design to face the many engineering tradeoffs encountered for true portability, including: (1) sampling systems of small sample volumes with minimal need for sheath hydrodynamic focusing both to avoid the need for large amounts of sheath fluid and to enable higher volumes of actual sample, (2) weight/power requirements that dictate use of super-bright LEDs as light sources, integrated “top hat” focusing optics to minimize the need for cell positioning and very small silicon photomultiplier sensors, with tightly integrated electronics (3) powered by small batteries or regenerative power sources such as solar, and (4) light-weight and robust enough for portability in potentially extreme environments. Initial prototyping used Raspberry Pi credit-card sized microcomputers, but longer-term development is being geared toward smartphone technologies. Smartphone technology can provide a powerful CPU, touch-screen and digital speech recognition interface, telecommunications via phone and internet, with a GPS chip to mark the location of the patient in the field. We are now using Motorola’s new Moto Z3 Play, a dual 12-megapixel/5-megapixel rear camera with 8-megapixel front camera, modular and open-architecture smartphone which allows building custom applications using hot-swappable accessories via Moto Development Kit modules, including externally-mountable Li-battery packs to power linked cytometry optics and electronics modules and microSD card storage with 512GB addressable memory linkable to other special purpose modules via USB-C connections. The device is software-configurable from a Linux workstation running Android Studio IDE with Java and Python programming.