How a Startup Built a Trade-Show-Ready Wearable, Electronics and Enclosure, in Six Weeks

An organizer offers a wearable startup a demo slot at a major manufacturing expo. The product is a wrist band that gives a quiet haptic cue when a warehouse worker repeatedly lifts with a bent wrist. The demo schedule includes board fabrication, assembly, firmware, and shipping, so design work must move in hours.

The engineering lead handled product and electronics. The mechanical engineer owned firmware. Their third teammate managed sales and the exhibit. Until that call, they had been testing an IMU breakout board taped to a silicone wrist strap. It showed wrist movement, but the board shifted during a lift and the vibration motor buzzed against a cable. The trade-show unit needed a stable sensor position, a protected charge port, and a housing visitors could wear.

The booth slot set the design boundary

The team agreed that the wearable would detect a defined wrist rotation and signal with a short vibration. It would not make a medical claim. The band needed to fit several wrist sizes, run through a work shift of demonstrations, and pair with a phone for a simple setup screen. The engineering lead put the product requirements and an envelope of 46 by 31 by 13 millimeters into the shared project.

The proposed board used a nRF52840 module, BMI270 six-axis IMU, DRV2605 haptic driver, a 250 mAh LiPo cell, and USB-C charging. A four-layer, 31 by 23 millimeter board placed the IMU near the strap's centerline. The engineering lead kept the radio antenna at the end away from the battery and motor leads. The charge indicator faced a small window in the upper shell.

The mechanical engineer wrote the firmware state plan in parallel: pairing, ready, movement cue, and charging. The team kept the six-week schedule visible. The electronics and mechanical design review took one afternoon. Board fabrication and assembly occupied the next two weeks. The mechanical engineer built the first firmware image while the engineering lead reviewed the enclosure and fit samples. The team reserved the final week for wear tests, packaging, and shipping.

Give the sensor a repeatable place on the wrist

The first strap sketch put the board on top of the wrist. A visiting warehouse supervisor tried the foam mock-up and showed where a glove cuff caught the edge. The engineering lead changed the capsule to sit slightly on the inner side of the wrist, where the IMU followed the hand rather than rotating around the strap.

The industrial designer shaped a 1.4-millimeter PC/ABS capsule with a TPU strap and two adjustable slots. A shallow silicone pad held the shell against the wrist. The haptic motor sat against a molded pocket in the lower housing, while the battery lay under the board. A 0.8-millimeter gasket protected the seam from sweat during repeated demonstrations.

The engineering lead imported the IMU and USB-C connector models into the assembly. The USB-C plug approached from the side, so a cable would not press against the hand when the wearer bent a wrist. The first X-ray view showed the haptic motor touching a board corner. The industrial designer widened its pocket by 1.6 millimeters and shifted a strap boss away from the antenna keep-out.

They checked the case's snap tabs for repeated opening. A small display was not needed, so the upper face stayed smooth except for the charge indicator. The team used a 3D print for the booth samples and a soft molded strap for the final wear trials. The lower shell had a curved contact face rather than a flat rectangle, which kept the IMU aligned when the wrist moved.

Three prompts from the six-week plan

Design a wrist wearable for warehouse staff that detects a repeated bent-wrist posture and gives a short haptic cue. Keep it light, fit several wrist sizes, and run through a work shift of product demonstrations.

Place the nRF52840 module, BMI270 IMU, DRV2605, 250 mAh cell, and USB-C charge path on a 31 by 23 millimeter board. Center the IMU on the strap axis and preserve the antenna space.

Shape the PC/ABS capsule around the wrist, with the motor touching its vibration pocket and the USB-C lead entering from the side. Check snap-tab access, gasket compression, and strap-boss clearance in the assembled view.

A full-device review fit into one afternoon

The engineering lead and the industrial designer checked the board inside the capsule before they sent the manufacturing package. The Flux agent built and routed the board, maintained the BOM, and updated the USB-C opening and standoffs with board changes. The mechanical engineer checked the selected sensor and haptic driver against their datasheets. The engineering lead reviewed the IMU orientation and approved the antenna region.

The team ran circuit simulation on the charging path and used design rule checks on the layout. They inspected the haptic motor, battery, strap bosses, and gasket in 3D. The final design package went to board assembly while the mechanical engineer kept firmware work moving on the same product requirements. The team did not confuse the design pass with the six-week production schedule.

The show unit used a four-layer 31 by 23 millimeter board with the nRF52840, BMI270, DRV2605, protected battery charging, and a side USB-C port. Its mechanical assembly combined the PC/ABS capsule, gasket, TPU strap, soft contact pad, snap tabs, and haptic pocket. The IMU stayed in the same orientation when the strap moved between wrist sizes.

The wearable reached the expo booth with firmware installed, a spare strap, and a quick-start card. Visitors could put it on, pair it, move their wrists, and feel the cue. A facilities operator asked for a wider strap slot for a winter sleeve. The engineering lead captured the request beside the model and returned to the team with a specific mechanical revision, not a vague styling note.

the startup's six-week plan worked because each discipline had a visible deliverable. The board could be assembled while the firmware developed. The case could be printed while the engineering lead checked sensor placement. Trade-show shipping remained a calendar task, but connected design changes took hours. The three-person team arrived with a working product and enough detail to discuss its next production run.

A wearable schedule for a short launch window

• Lock the user's movement, cue, fit range, battery target, and service action.
• Place the IMU in a repeatable orientation relative to the band.
• Review the battery, motor, charging port, and strap geometry together.
• Keep board assembly, firmware, enclosure samples, and shipping on separate schedule lines.
• Test snap tabs, strap fit, haptic contact, and charge access with actual wearers.
• Send manufacturing one current board, BOM, and enclosure revision.

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