RE9 Blood Specimen Analyzer Puzzle — 4×4 Vial Solution

RE9's Blood Specimen Analyzer is a 4×4 grid puzzle in the ARK Facility Sterilization Chamber. You need to match 4 blood-type vials to the correct slots using the blood-type compatibility chart found on the wall. Get it wrong twice and the chamber locks. Full solution + chart explained below.

How the analyzer works

The Blood Specimen Analyzer sits on a steel pedestal in the center of the Sterilization Chamber. It has 4 slots arranged left-to-right (positions 1, 2, 3, 4) and you pick up 4 blood vials from the fridge along the north wall. Each vial is labeled with a blood type (A+, A−, B+, B−, O+, O−, AB+, AB−).

On the south wall there's a faded chart showing which blood type can transfuse into which (the universal donor/recipient rules). Your job is to place 4 vials so that each vial in position N can transfuse into the vial in position N+1 — i.e. a "donation chain" from left to right.

Blood-type chart (decoded)

Here's the chart on the wall, simplified. An arrow A → B means "type A can donate to type B".

The solution (4 vials, left to right)

You need a donation chain. The intended (and only) chain that uses the 4 vials Grace finds in the fridge is:

Why this works:

• O− → A−: O− is universal donor, so it donates to A− ✓
• A− → A+: A− can donate to A+ (negative donates to positive within same letter) ✓
• A+ → AB+: A+ donates to AB+ ✓
• AB+ in slot 4 — universal recipient, terminates the chain ✓

Step-by-step walkthrough

1. Enter Sterilization Chamber via the Lab Access Card A door (Lower Lab → west corridor).
2. Pick up all 4 vials from the fridge on the north wall. The fridge contains: O−, A−, A+, AB+. You don't need any other vials.
3. Read the blood-type chart on the south wall (or just use the solution above).
4. Walk to the analyzer pedestal in the center.
5. Place vials in this order: Slot 1 = O−, Slot 2 = A−, Slot 3 = A+, Slot 4 = AB+.
6. Press the green Analyze button. Chamber hums for 8 sec, then lights turn green.
7. Lab Access Card B drops from a slot on the right side of the pedestal. Pick it up.
8. First Aid Spray spawns on the analyzer's top tray. Grab it.
9. Card B opens the next door — leads to the Quartz Puzzle Hub.

Tips & what NOT to do

1. Don't waste vials on wrong slots — placing a vial in the wrong slot doesn't consume it, but 2 wrong configurations triggers a 60-sec lockout. Use the chart.
2. O− goes in slot 1 always — universal donor is the only vial that can sit at the start of any chain.
3. AB+ goes in slot 4 always — universal recipient is the only vial that can sit at the end.
4. Slots 2 and 3 must bridge — A−/A+ pair is the only valid bridge with the vials Grace finds.
5. Insanity mode bonus: solving on the first try awards a Hemorrhetic Injector in the analyzer's bottom drawer (skip if you got 1+ wrong tries).
6. NG+ wisdom: the fridge contents don't change between difficulties — the solution is always O− → A− → A+ → AB+.