Haptic Synthetic Jet

This is a tutorial for Expressive, Scalable, Mid-air Haptics with Synthetic Jets . This paper was published in the ACM Transactions on Computer-Human Interaction in January 2024, and presented at CHI 2024.

Check out the Github Repository here. Contact me with questions here!

Non-contact, mid-air haptic devices have been utilized for a wide variety of experiences, including those in extended reality, public displays, medical, and automotive domains. In this work, we explore the use of synthetic jets as a promising and under-explored mid-air haptic feedback method. We show how synthetic jets can scale from compact, low-powered devices, all the way to large, long-range, and steerable devices. We built seven functional prototypes targeting different application domains to illustrate the broad applicability of our approach. These example devices are capable of rendering complex haptic effects, varying in both time and space.

The BoM is linked here - these are just the materials we use, but synjets can be built with many different speakers, for a wide variety of devices!

Choose the speaker you are using. Roughly, the larger the speaker, the farther/stronger the range of the synjet.

Fabricate the enclosure. All the design files are in the Github repo, compatible with the speakers we've used. We laser cut these out of acrylic to put on the speakers. If you are using our tiniest speaker, instead cut a small hole out of cardstock and glue that on top.

The small class D amplifier can be powered either through a 5V USB connection from your computer, or a 9-12V power adapter. Either way, strip one end of the cable and attach power to VCC and ground to GND on the amplifier.

Attach wires to the two terminals of your speaker, and then wire them to R+ and R- (or L+ and L-). The polarity doesn't really matter.

You can use the other side for another synjet.

Plug in the USB power and an audio cable from your computer to the amplifier.

Using Audacity (or any other audio software, like Audition), play an appropriate sine wave for your synjet. Start with the resonant frequency of your speaker (which can be found on the online spec sheet), and then you can tune it from there. You can also find demo WAV files in the "Stimuli Recognition Study" folder on the Github.

Slowly turn the knob up, if everything went right you should be able to feel a stream of air.