The document discusses Koç University's research on optical micro-mechatronic systems utilizing FR4 technology in printed circuit boards (PCBs) for electromagnetic actuation. It highlights the advantages of FR4, such as precision in design and the integration of various components, while detailing the operation and dynamic focusing capabilities of a laser scanner. Experimental results show the system's efficacy in scanning barcodes over varying ranges.

1. Koç University
Electromagnetically Actuated Optical Micro-
Mechatronic Systems Integrated on PCB
SerhanO. ISIKMAN
Advisor: Prof. Hakan Urey
http://mems.ku.edu.tr
http://www.serhanisikman.com 1

2. FR4 Technology: Printed Circuit Boards
(PCBs) as Actuated Platforms
 FR4 (Flame Retardant – Type 4) is the main substrate used in today’s
PCBs
 PCB sheets can be cut in the desired shape with high precision (<30um
precision) using standard, cost-effective PCB technology
 Different structural thicknesses available for design flexibility: 130um,

3. FR4 Technology: Main Advantages
 Uses existing standard PCB technology
 Comes with a seed copper layer suitable for electrical
interconnects, electro-magnetic actuation, and electro-
deposition of other metals (e.g. Nickel, permalloy)
 Well engineered material with excellent
electrical, thermal, and mechanical properties
 Compliant but strong material: Allows large deflections at
low frequencies, without vacuum !
 Can integrate electrical, mechanical, and optical
components on the same board for improved robustness
and form factor

4. Large scan-angle is achieved over an extended
depth-of-field using the FR4 scanner technology
Collection lens:
collects the light that is reflected off the
object-of-interest, and focuses it to an on-
chip, die-level detector underneath. Note
that the detector is powered through the
interconnects on the PCB platform, which is Torsionalflexures:
an additional flexibility of FR4 scanners (stress-resistant design to bear
large—angle deflections)
Opto-mechanical holder:
to mount the synchronously
scanned lenses
Focusing lens:
focuses the laser-light to a
distance, which is dynamically
changed as the laser is
actuated in/out of plane
Electro-coil:
“Laser-plunger”: to actuate the scanner in torsion
flexures actuate the VCSEL out-of-planew.r.t. the mode (for scanning) resonantly at
focusing lens for changing the focal-plane of scanning 50 Hz

5. Large scan-angle is achieved over an extended
depth-of-field using the FR4 scanner technology
(moving magnet
(moving magnet
scheme)
scheme)
Torsion @ 60 Hz Plunger @ 150 Hz

6. FR4 Laser Scanner with Dynamic Focusing
Dynamic Focusing Operation -
 Plunger is actuated in moving-coil fashion
 4 copper traces are patterned on the 500um wide plunger:
1 for laser diode (VCSEL), 3 for electro-magnetic actuation
 Plunger moves the laser diode out-of-plane with respect the lens to
modulate the beam waist location

7. FR4 Scanner with Scanned Detection + Dynamic
Focusing for Extended Depth-of-field Imaging

8. Barcodes with 125um lines are rapidly scanned over a 10cm
range, while more common bar codes (with 500um lines) are
scanned up to a 60cm range using the same bar-code reader
- experimental results -