OpenDrop Digital Microfluidics Platform

Jul 15, 2020 3 min read Hardware, Benchtop, Computers, Software

OpenDrop a modular, open source digital microfludics platform for research purposes. The device uses recent electro-wetting technology to control small droplets of liquids. Potential applications are lab on a chip devices for automating processes of digital biology.

The OpenDrop V4 is modular electrowetting controller. The driver board is equipped with a connector that can host a circuit board cartridge with a 14×8 electrode array and 4 reservoirs. The liquids stay on a thin, hydrophobic foil laminated to the circuit board . The device is powered from USB though an included USB-C cable. All the voltage level are generated on the device and can be set with the built in soft menu from 150-300 Volts, DC or AC.

OpenDrop Cartridges The modular concepts of the OpenDrop V4 allows different configurations of cartridges: A gold coated electrode array board that can be coated with any dielectric layer and hydrophobic coating to make cartridges for topless digital microfluidic applications using readily available materials.The OpenDrop V4 Cartridge is a close-cell cartridge capable of “move, mix, split and reservoir dispensing”. The 4×8 electrode array and 4 reservoirs are laminated with a 15um ETFE foil, hydrophobic coating and ITO top cover.

Programming The OpenDrop V4 can be operated standalone and droplets can be moved through the built in joystick. A control software to program sequences of patterns from a computer is available as a free download. The board is also compatible with Adafruit Feather M0 controller boards and can be reprogrammed through the free Arduino IDE for custom specific applications. A sample code with the instruction to activate electrodes can be found on the OpenDrop GitHub.

Features:

Modular Cartridge System - Connector to connect electrode board with up to 128 channels - Gold coated 14×8 electrodes array, 2.75 mm x 2.75 mm in size, 4mil gaps
Reservoirs – the new electrode array features 4 CT-type reservoirs
AC and DC voltage generated on the device form USB power. True AC voltage driving capability (up to 300VAC).
32bit AVR SAMD21G18 microprocessor with plenty of memory and power - Electronic settings for voltage level, frequency and AC/DC selection - Electronic reading of actual voltage level - One connector for communication and powering (USB-C) - Optical isolation of the high-voltage electronics trough opto-couplers and PhotoMOS - New polyphonic audio amplifier and speaker (it’s a synth!) - Cartridge presence detection - Feedback amplifier - Super flat OLED Display - Nice joystick and 2 buttons, 3 LEDs - Reset button - All files open source, designed on KiCAD