InvisiSpeech is the first intraoral interface embedding a Voice Pickup Unit (VPU) sensor, enabling private invisible silent speech. (a) User wearing a InvisiSpeech interface on left side. (b) InvisiSpeech consists of two components: (1) the 3D-printed biocompatible brace, (2) the integrated flexible PCB with VPU sensor, bluetooth microcontroller, latching switch, magnetic charging connector and battery. (c) InvisiSpeech enables several applications such as hands-free interaction, subtle communication and discreet interaction.
InvisiSpeech
Wearable Computing
Nov 2025 - April 2026
Project Overview
InvisiSpeech is an intraoral interface that remains hidden from outside view and supports silent speech input with minimal lip movement and without drawing visual attention. Our custom flex-PCB device is housed in a biocompatible SLA-printed dental brace and attaches around the back molar. This mount couples a voice-pickup sensor to the tooth for input sensing, which our embedded microcontroller transfers via Bluetooth. We demonstrate three applications of the system: hands-free interaction in public, discreet interaction in a quiet public place, and subtle communication in a privacy-sensitive context.
Device Design
(a) Rendering of the InvisiSpeech device and its embedded components, including the brace, battery, and flexible PCB. (b) Mechanical structure of InvisiSpeech, illustrating how the device conforms to the dental arch and the placement of the FPCB within the intraoral form factor. (c) PCB layout of the flexible board, where the front side (top) integrates computing, sensing, and interface components, and the back side (bottom) accommodates the remaining elements.
Assembling & Fabrication
Process
(a) Attaching the battery to the flexible circuit board through soldering. (b) Encapsulating the device components by filling the housing with resin. (c) Sealing the charging interface to ensure waterproofing. (d) Applying flexible material into the switch area to preserve functionality. (e) Finalizing the assembly by curing the device under UV light.
System Architecture
Overview of the InvisiSpeech system architecture. The microcontroller unit is the central hub that communicates with the sensor.
Applications
(a) Subtle communication during a meeting, enabling users to query information without speaking aloud. (b) On-the-go interaction in public, allowing users to send messages discreetly while moving. (c) Discreet interaction in quiet environments, enabling silent control of devices without disturbing others.
