Hardware_Recommended

See the individual guides for conceptual and technical information on the hardware aspects of the behavioral system (pumps, display screens, bluetooth & usb, electronics & circuit). These guides are intended to help users make informed decisions on the type of hardware that best suits their application. The recommendation below is specific to one of our most recent implemented systems and, much like the code, is only meant to serve as a working starting point. We encourage you to purchase any of these items and try them before committing to a particular implementation.

Touchscreen - Google Pixel C

The touchscreen is the centerpiece of the system; it takes user touches as input, outputs the stimuli (audio/video), and communicates wirelessly with the cloud for the data storage. There are a number of factors to consider in choosing a tablet including the screen dpi, the touch sensitivity, the OS, the locations of ports and home screen buttons, the type of power connector, and of course, cost. We chose the Pixel C not only because it uses android and runs the chrome browser but because, as a google device, it receives the latest android OS updates automatically (unlike Samsung tablets). In addition, the pixel C has a USB type-C port which allows both charging (with USB battery pack) and communication (with arduino). The Pixel C has 308 dpi which is above average for a tablet, and we like that there are no physical home screen buttons on the screen face that we would have to cover up or inadvertently touch. Also, the USB port and power button are placed toward one end which works for our current configuration. The drawbacks of the Pixel C are that it is expensive and now no longer made by Google. Viable alternatives include the Samsung Galaxy Tab S3 and the Asus ZenPad 3S 10.

Pump - Takasago SDMP306D or TCS Micropumps D250S-L

The Takasago piezoelectric pumps run smoothly and quietly and provide a continuously controllable volume output. Because they are piezoelectric, they are low power (~0.1W) but can only do flow rates up to 7mL/min. For larger flow rates, we recommend the TCS diaphragm pumps which aren't as continuously controllable but are quite powerful while still being fairly low power (1.8W).

Microcontroller - Arduino Leonardo

The Leonardo contains more digital and analog IO than typically needed for a behavioral system, but at the same time, the larger form factor (as compared to the nano) allows more freedom to expand inputs in the future. Furthermore, a bonus is that the Leonardo draws enough power to keep most USB batteries from shutting off even if they have an auto shut-off circuit, which most do. The smaller arduino nano and redbearlabs nano would often lead to the battery shutting off when the tablet was charged when in reality the battery is needed to power the low power microcontroller. Arduino is also recommended because arduino is now integrated with the webusb api.

USB Battery Pack - Yoobao 20000mAH Battery

There are many USB battery packs out there. We simply liked this one because it has a digital display of remaining battery life and has both micro-usb and usb-c ports. We estimate that 20000mAH is about the size needed for a full charge of a 10" sized tablet.

Bluetooth Scale - Motif Mentor

Ideally, a bluetooth scale would have an API available, but most don't, and we ended up reverse engineering them by finding the service/characteristic transmitting the weight and decoding that using known weights. So far, our favorite scale is the Motif Mentor. It is small and thin, has a good range 3kg while being precise ~0.1g. It's auto-shutoff time is 5 minutes which is better than most. But what is really unique about the Mentor is that it has no visible buttons, so it is just a black box that can be read remotely. The Acaia line of coffee scales has similar accuracy as the Mentor but costs significantly more, and does not provide access to the weights. However, Acaia is planning on releasing an API to make their high quality scales open, so you may want to keep an eye for that. For any larger weights, you should be in luck as there is a plethora of bluetooth scales for weighing in ranges of 3kg and up.