From fbf0e9a2ccabb4802b505bb64f4111e6fb52981e Mon Sep 17 00:00:00 2001
From: Rick Wierenga <rick_wierenga@icloud.com>
Date: Thu, 2 Oct 2025 17:16:03 -0700
Subject: [PATCH 1/6] lh.{aspirate,dispense} mix parameter

---
 .../backends/opentrons_backend.py             | 26 +++++++++++++++++++
 pylabrobot/liquid_handling/liquid_handler.py  | 11 ++++++--
 pylabrobot/liquid_handling/standard.py        | 13 ++++++++++
 3 files changed, 48 insertions(+), 2 deletions(-)

diff --git a/pylabrobot/liquid_handling/backends/opentrons_backend.py b/pylabrobot/liquid_handling/backends/opentrons_backend.py
index b17c75b0822..86656df1b76 100644
--- a/pylabrobot/liquid_handling/backends/opentrons_backend.py
+++ b/pylabrobot/liquid_handling/backends/opentrons_backend.py
@@ -420,6 +420,19 @@ async def aspirate(self, ops: List[SingleChannelAspiration], use_channels: List[
       pipette_id=pipette_id,
     )
 
+    if op.mix is not None:
+      for _ in range(op.mix.repetitions):
+        ot_api.lh.aspirate_in_place(
+          volume=op.mix.volume,
+          flow_rate=op.mix.flow_rate,
+          pipette_id=pipette_id,
+        )
+        ot_api.lh.dispense_in_place(
+          volume=op.mix.volume,
+          flow_rate=op.mix.flow_rate,
+          pipette_id=pipette_id,
+        )
+
     ot_api.lh.aspirate_in_place(
       volume=volume,
       flow_rate=flow_rate,
@@ -490,6 +503,19 @@ async def dispense(self, ops: List[SingleChannelDispense], use_channels: List[in
       pipette_id=pipette_id,
     )
 
+    if op.mix is not None:
+      for _ in range(op.mix.repetitions):
+        ot_api.lh.aspirate_in_place(
+          volume=op.mix.volume,
+          flow_rate=op.mix.flow_rate,
+          pipette_id=pipette_id,
+        )
+        ot_api.lh.dispense_in_place(
+          volume=op.mix.volume,
+          flow_rate=op.mix.flow_rate,
+          pipette_id=pipette_id,
+        )
+
     traversal_location = op.resource.get_absolute_location("c", "c", "cavity_bottom") + op.offset
     traversal_location.z = self.traversal_height
     await self.move_pipette_head(
diff --git a/pylabrobot/liquid_handling/liquid_handler.py b/pylabrobot/liquid_handling/liquid_handler.py
index 8f5281c59a7..9188e3c6802 100644
--- a/pylabrobot/liquid_handling/liquid_handler.py
+++ b/pylabrobot/liquid_handling/liquid_handler.py
@@ -69,6 +69,7 @@
   Drop,
   DropTipRack,
   GripDirection,
+  Mix,
   MultiHeadAspirationContainer,
   MultiHeadAspirationPlate,
   MultiHeadDispenseContainer,
@@ -816,6 +817,7 @@ async def aspirate(
     liquid_height: Optional[List[Optional[float]]] = None,
     blow_out_air_volume: Optional[List[Optional[float]]] = None,
     spread: Literal["wide", "tight", "custom"] = "wide",
+    mix: Optional[List[Mix]] = None,
     **backend_kwargs,
   ):
     """Aspirate liquid from the specified wells.
@@ -963,8 +965,9 @@ async def aspirate(
         tip=t,
         blow_out_air_volume=bav,
         liquids=lvs,
+        mix=m,
       )
-      for r, v, o, fr, lh, t, bav, lvs in zip(
+      for r, v, o, fr, lh, t, bav, lvs, m in zip(
         resources,
         vols,
         offsets,
@@ -973,6 +976,7 @@ async def aspirate(
         tips,
         blow_out_air_volume,
         liquids,
+        mix or [None] * len(use_channels),
       )
     ]
 
@@ -1039,6 +1043,7 @@ async def dispense(
     liquid_height: Optional[List[Optional[float]]] = None,
     blow_out_air_volume: Optional[List[Optional[float]]] = None,
     spread: Literal["wide", "tight", "custom"] = "wide",
+    mix: Optional[List[Mix]] = None,
     **backend_kwargs,
   ):
     """Dispense liquid to the specified channels.
@@ -1193,8 +1198,9 @@ async def dispense(
         tip=t,
         liquids=lvs,
         blow_out_air_volume=bav,
+        mix=m,
       )
-      for r, v, o, fr, lh, t, bav, lvs in zip(
+      for r, v, o, fr, lh, t, bav, lvs, m in zip(
         resources,
         vols,
         offsets,
@@ -1203,6 +1209,7 @@ async def dispense(
         tips,
         blow_out_air_volume,
         liquids,
+        mix or [None] * len(use_channels),
       )
     ]
 
diff --git a/pylabrobot/liquid_handling/standard.py b/pylabrobot/liquid_handling/standard.py
index bca3971f094..ce94c420df7 100644
--- a/pylabrobot/liquid_handling/standard.py
+++ b/pylabrobot/liquid_handling/standard.py
@@ -59,6 +59,7 @@ class SingleChannelAspiration:
   liquid_height: Optional[float]
   blow_out_air_volume: Optional[float]
   liquids: List[Tuple[Optional[Liquid], float]]
+  mix: Optional[Mix] = None
 
 
 @dataclass(frozen=True)
@@ -71,6 +72,18 @@ class SingleChannelDispense:
   liquid_height: Optional[float]
   blow_out_air_volume: Optional[float]
   liquids: List[Tuple[Optional[Liquid], float]]
+  mix: Optional[Mix] = None
+
+
+@dataclass(frozen=True)
+class Mix:
+  # resource: Container
+  # offset: Coordinate
+  # tip: Tip
+  volume: float
+  repetitions: int
+  flow_rate: float
+  # liquid_height: float
 
 
 @dataclass(frozen=True)

From aa8db18a911999f2a5a0f2362049cb96067f031f Mon Sep 17 00:00:00 2001
From: Rick Wierenga <rick_wierenga@icloud.com>
Date: Thu, 2 Oct 2025 17:24:22 -0700
Subject: [PATCH 2/6] support on {STAR,Vantage}.{aspirate,dispense}

---
 .../backends/hamilton/STAR_backend.py         | 32 +++++++++----------
 .../backends/hamilton/vantage_backend.py      | 22 +++++++++----
 2 files changed, 32 insertions(+), 22 deletions(-)

diff --git a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
index 2434204f118..0b01bdcee94 100644
--- a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
+++ b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
@@ -1712,6 +1712,11 @@ async def aspirate(
           and 360. Defaults to well bottom + liquid height. Should use absolute z.
     """
 
+    if mix_volume is not None or mix_cycles is not None or mix_speed is not None:
+      raise NotImplementedError(
+        "Mixing through backend kwargs is deprecated. Use the `mix` parameter of LiquidHandler.aspirate instead."
+      )
+
     x_positions, y_positions, channels_involved = self._ops_to_fw_positions(ops, use_channels)
 
     n = len(ops)
@@ -1817,17 +1822,12 @@ async def aspirate(
         hlc.aspiration_settling_time if hlc is not None else 0.0 for hlc in hamilton_liquid_classes
       ],
     )
-    mix_volume = _fill_in_defaults(mix_volume, [0.0] * n)
-    mix_cycles = _fill_in_defaults(mix_cycles, [0] * n)
+    mix_volume = [op.mix.volume if op.mix is not None else 0.0 for op in ops]
+    mix_cycles = [op.mix.repetitions if op.mix is not None else 0 for op in ops]
     mix_position_from_liquid_surface = _fill_in_defaults(
       mix_position_from_liquid_surface, [0.0] * n
     )
-    mix_speed = _fill_in_defaults(
-      mix_speed,
-      default=[
-        hlc.aspiration_mix_flow_rate if hlc is not None else 50.0 for hlc in hamilton_liquid_classes
-      ],
-    )
+    mix_speed = [op.mix.flow_rate if op.mix is not None else 0.0 for op in ops]
     mix_surface_following_distance = _fill_in_defaults(mix_surface_following_distance, [0.0] * n)
     limit_curve_index = _fill_in_defaults(limit_curve_index, [0] * n)
 
@@ -2007,6 +2007,11 @@ async def dispense(
         documentation. Dispense mode 4.
     """
 
+    if mix_volume is not None or mix_cycles is not None or mix_speed is not None:
+      raise NotImplementedError(
+        "Mixing through backend kwargs is deprecated. Use the `mix` parameter of LiquidHandler.dispense instead."
+      )
+
     x_positions, y_positions, channels_involved = self._ops_to_fw_positions(ops, use_channels)
 
     n = len(ops)
@@ -2113,17 +2118,12 @@ async def dispense(
         hlc.dispense_settling_time if hlc is not None else 0.0 for hlc in hamilton_liquid_classes
       ],
     )
-    mix_volume = _fill_in_defaults(mix_volume, [0.0] * n)
-    mix_cycles = _fill_in_defaults(mix_cycles, [0] * n)
+    mix_volume = [op.mix.volume if op.mix is not None else 0.0 for op in ops]
+    mix_cycles = [op.mix.repetitions if op.mix is not None else 0 for op in ops]
     mix_position_from_liquid_surface = _fill_in_defaults(
       mix_position_from_liquid_surface, [0.0] * n
     )
-    mix_speed = _fill_in_defaults(
-      mix_speed,
-      default=[
-        hlc.dispense_mix_flow_rate if hlc is not None else 50.0 for hlc in hamilton_liquid_classes
-      ],
-    )
+    mix_speed = [op.mix.flow_rate if op.mix is not None else 0.0 for op in ops]
     mix_surface_following_distance = _fill_in_defaults(mix_surface_following_distance, [0.0] * n)
     limit_curve_index = _fill_in_defaults(limit_curve_index, [0] * n)
 
diff --git a/pylabrobot/liquid_handling/backends/hamilton/vantage_backend.py b/pylabrobot/liquid_handling/backends/hamilton/vantage_backend.py
index d33cf346d81..92650354566 100644
--- a/pylabrobot/liquid_handling/backends/hamilton/vantage_backend.py
+++ b/pylabrobot/liquid_handling/backends/hamilton/vantage_backend.py
@@ -622,6 +622,11 @@ async def aspirate(
         determined automatically based on the tip and liquid used.
     """
 
+    if mix_volume is not None or mix_cycles is not None or mix_speed is not None:
+      raise NotImplementedError(
+        "Mixing through backend kwargs is deprecated. Use the `mix` parameter of LiquidHandler.dispense instead."
+      )
+
     x_positions, y_positions, channels_involved = self._ops_to_fw_positions(ops, use_channels)
 
     if jet is None:
@@ -730,12 +735,12 @@ async def aspirate(
       ],
       swap_speed=[round(ss * 10) for ss in swap_speed or [2] * len(ops)],
       settling_time=[round(st * 10) for st in settling_time or [1] * len(ops)],
-      mix_volume=[round(mv * 100) for mv in mix_volume or [0] * len(ops)],
-      mix_cycles=mix_cycles or [0] * len(ops),
+      mix_volume=[round(op.mix.volume * 100) if op.mix is not None else 0 for op in ops],
+      mix_cycles=[op.mix.repetitions if op.mix is not None else 0 for op in ops],
       mix_position_in_z_direction_from_liquid_surface=[
         round(mp) for mp in mix_position_in_z_direction_from_liquid_surface or [0] * len(ops)
       ],
-      mix_speed=[round(ms * 10) for ms in mix_speed or [250] * len(ops)],
+      mix_speed=[round(op.mix.flow_rate * 10) if op.mix is not None else 0 for op in ops],
       surface_following_distance_during_mixing=[
         round(sfdm * 10) for sfdm in surface_following_distance_during_mixing or [0] * len(ops)
       ],
@@ -808,6 +813,11 @@ async def dispense(
         documentation. Dispense mode 4.
     """
 
+    if mix_volume is not None or mix_cycles is not None or mix_speed is not None:
+      raise NotImplementedError(
+        "Mixing through backend kwargs is deprecated. Use the `mix` parameter of LiquidHandler.dispense instead."
+      )
+
     x_positions, y_positions, channels_involved = self._ops_to_fw_positions(ops, use_channels)
 
     if jet is None:
@@ -922,12 +932,12 @@ async def dispense(
       pressure_lld_sensitivity=pressure_lld_sensitivity or [1] * len(ops),
       swap_speed=[round(ss * 10) for ss in swap_speed or [1] * len(ops)],
       settling_time=[round(st * 10) for st in settling_time or [0] * len(ops)],
-      mix_volume=[round(mv * 100) for mv in mix_volume or [0] * len(ops)],
-      mix_cycles=mix_cycles or [0] * len(ops),
+      mix_volume=[round(op.mix.volume * 100) if op.mix is not None else 0 for op in ops],
+      mix_cycles=[op.mix.repetitions if op.mix is not None else 0 for op in ops],
       mix_position_in_z_direction_from_liquid_surface=[
         round(mp) for mp in mix_position_in_z_direction_from_liquid_surface or [0] * len(ops)
       ],
-      mix_speed=[round(ms * 10) for ms in mix_speed or [1] * len(ops)],
+      mix_speed=[round(op.mix.flow_rate * 10) if op.mix is not None else 0 for op in ops],
       surface_following_distance_during_mixing=[
         round(sfdm * 10) for sfdm in surface_following_distance_during_mixing or [0] * len(ops)
       ],

From 5ca0f47e93a9bd3b916a55266b308415ef58f413 Mon Sep 17 00:00:00 2001
From: Rick Wierenga <rick_wierenga@icloud.com>
Date: Thu, 2 Oct 2025 17:46:21 -0700
Subject: [PATCH 3/6] {aspirate,dispene}96

---
 .../backends/hamilton/STAR_backend.py         | 24 +++++++----
 .../backends/hamilton/vantage_backend.py      | 24 +++++++----
 pylabrobot/liquid_handling/liquid_handler.py  | 41 +++++++++----------
 pylabrobot/liquid_handling/standard.py        |  4 ++
 4 files changed, 58 insertions(+), 35 deletions(-)

diff --git a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
index 0b01bdcee94..04270d71939 100644
--- a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
+++ b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
@@ -2327,6 +2327,11 @@ async def aspirate96(
       limit_curve_index: The index of the limit curve to use.
     """
 
+    if mix_volume != 0 or mix_cycles != 0 or speed_of_mix != 0:
+      raise NotImplementedError(
+        "Mixing through backend kwargs is deprecated. Use the `mix` parameter of LiquidHandler.aspirate96 instead."
+      )
+
     assert self.core96_head_installed, "96 head must be installed"
 
     # get the first well and tip as representatives
@@ -2444,11 +2449,11 @@ async def aspirate96(
       gamma_lld_sensitivity=gamma_lld_sensitivity,
       swap_speed=round(swap_speed * 10),
       settling_time=round(settling_time * 10),
-      mix_volume=round(mix_volume * 10),
-      mix_cycles=mix_cycles,
+      mix_volume=round(aspiration.mix.volume * 10) if aspiration.mix is not None else 0,
+      mix_cycles=aspiration.mix.repetitions if aspiration.mix is not None else 0,
       mix_position_from_liquid_surface=round(mix_position_from_liquid_surface * 10),
       surface_following_distance_during_mix=round(surface_following_distance_during_mix * 10),
-      speed_of_mix=round(speed_of_mix * 10),
+      speed_of_mix=round(aspiration.mix.flow_rate * 10) if aspiration.mix is not None else 0,
       channel_pattern=channel_pattern,
       limit_curve_index=limit_curve_index,
       tadm_algorithm=False,
@@ -2482,7 +2487,7 @@ async def dispense96(
     mixing_cycles: int = 0,
     mixing_position_from_liquid_surface: float = 0,
     surface_following_distance_during_mixing: float = 0,
-    speed_of_mixing: float = 120.0,
+    speed_of_mixing: float = 0.0,
     limit_curve_index: int = 0,
     cut_off_speed: float = 5.0,
     stop_back_volume: float = 0,
@@ -2523,6 +2528,11 @@ async def dispense96(
       stop_back_volume: Unknown.
     """
 
+    if mixing_volume != 0 or mixing_cycles != 0 or speed_of_mixing != 0:
+      raise NotImplementedError(
+        "Mixing through backend kwargs is deprecated. Use the `mix` parameter of LiquidHandler.dispense instead."
+      )
+
     assert self.core96_head_installed, "96 head must be installed"
 
     # get the first well and tip as representatives
@@ -2628,11 +2638,11 @@ async def dispense96(
       gamma_lld_sensitivity=gamma_lld_sensitivity,
       swap_speed=round(swap_speed * 10),
       settling_time=round(settling_time * 10),
-      mixing_volume=round(mixing_volume * 10),
-      mixing_cycles=mixing_cycles,
+      mixing_volume=round(dispense.mix.volume * 10) if dispense.mix is not None else 0,
+      mixing_cycles=dispense.mix.repetitions if dispense.mix is not None else 0,
       mixing_position_from_liquid_surface=round(mixing_position_from_liquid_surface * 10),
       surface_following_distance_during_mixing=round(surface_following_distance_during_mixing * 10),
-      speed_of_mixing=round(speed_of_mixing * 10),
+      speed_of_mixing=round(dispense.mix.flow_rate * 10) if dispense.mix is not None else 0,
       channel_pattern=channel_pattern,
       limit_curve_index=limit_curve_index,
       tadm_algorithm=False,
diff --git a/pylabrobot/liquid_handling/backends/hamilton/vantage_backend.py b/pylabrobot/liquid_handling/backends/hamilton/vantage_backend.py
index 92650354566..6d9d42d51be 100644
--- a/pylabrobot/liquid_handling/backends/hamilton/vantage_backend.py
+++ b/pylabrobot/liquid_handling/backends/hamilton/vantage_backend.py
@@ -1038,7 +1038,7 @@ async def aspirate96(
     mix_cycles: int = 0,
     mix_position_in_z_direction_from_liquid_surface: float = 0,
     surface_following_distance_during_mixing: float = 0,
-    mix_speed: float = 2,
+    mix_speed: float = 0,
     limit_curve_index: int = 0,
     tadm_channel_pattern: Optional[List[bool]] = None,
     tadm_algorithm_on_off: int = 0,
@@ -1056,6 +1056,11 @@ async def aspirate96(
     """
     # assert self.core96_head_installed, "96 head must be installed"
 
+    if mix_volume != 0 or mix_cycles != 0 or mix_speed != 0:
+      raise NotImplementedError(
+        "Mixing through backend kwargs is deprecated. Use the `mix` parameter of LiquidHandler.dispense96 instead."
+      )
+
     if isinstance(aspiration, MultiHeadAspirationPlate):
       plate = aspiration.wells[0].parent
       assert isinstance(plate, Plate), "MultiHeadAspirationPlate well parent must be a Plate"
@@ -1151,15 +1156,15 @@ async def aspirate96(
       lld_sensitivity=lld_sensitivity,
       swap_speed=round(swap_speed * 10),
       settling_time=round(settling_time * 10),
-      mix_volume=round(mix_volume * 100),
-      mix_cycles=mix_cycles,
+      mix_volume=round(aspiration.mix.volume * 100) if aspiration.mix is not None else 0,
+      mix_cycles=aspiration.mix.repetitions if aspiration.mix is not None else 0,
       mix_position_in_z_direction_from_liquid_surface=round(
         mix_position_in_z_direction_from_liquid_surface * 100
       ),
       surface_following_distance_during_mixing=round(
         surface_following_distance_during_mixing * 100
       ),
-      mix_speed=round(mix_speed * 10),
+      mix_speed=round(aspiration.mix.flow_rate * 10) if aspiration.mix is not None else 0,
       limit_curve_index=limit_curve_index,
       tadm_channel_pattern=tadm_channel_pattern,
       tadm_algorithm_on_off=tadm_algorithm_on_off,
@@ -1215,6 +1220,11 @@ async def dispense96(
         determined based on the jet, blow_out, and empty parameters.
     """
 
+    if mix_volume != 0 or mix_cycles != 0 or mix_speed is not None:
+      raise NotImplementedError(
+        "Mixing through backend kwargs is deprecated. Use the `mix` parameter of LiquidHandler.dispense96 instead."
+      )
+
     if isinstance(dispense, MultiHeadDispensePlate):
       plate = dispense.wells[0].parent
       assert isinstance(plate, Plate), "MultiHeadDispensePlate well parent must be a Plate"
@@ -1313,13 +1323,13 @@ async def dispense96(
       side_touch_off_distance=round(side_touch_off_distance * 10),
       swap_speed=round(swap_speed * 10),
       settling_time=round(settling_time * 10),
-      mix_volume=round(mix_volume * 10),
-      mix_cycles=mix_cycles,
+      mix_volume=round(dispense.mix.volume * 100) if dispense.mix is not None else 0,
+      mix_cycles=dispense.mix.repetitions if dispense.mix is not None else 0,
       mix_position_in_z_direction_from_liquid_surface=round(
         mix_position_in_z_direction_from_liquid_surface * 10
       ),
       surface_following_distance_during_mixing=round(surface_following_distance_during_mixing * 10),
-      mix_speed=round(mix_speed * 10),
+      mix_speed=round(dispense.mix.flow_rate * 10) if dispense.mix is not None else 0,
       limit_curve_index=limit_curve_index,
       tadm_channel_pattern=tadm_channel_pattern,
       tadm_algorithm_on_off=tadm_algorithm_on_off,
diff --git a/pylabrobot/liquid_handling/liquid_handler.py b/pylabrobot/liquid_handling/liquid_handler.py
index 9188e3c6802..9aee1fc3913 100644
--- a/pylabrobot/liquid_handling/liquid_handler.py
+++ b/pylabrobot/liquid_handling/liquid_handler.py
@@ -1624,6 +1624,7 @@ async def aspirate96(
     flow_rate: Optional[float] = None,
     liquid_height: Optional[float] = None,
     blow_out_air_volume: Optional[float] = None,
+    mix: Optional[Mix] = None,
     **backend_kwargs,
   ):
     """Aspirate from all wells in a plate or from a container of a sufficient size.
@@ -1635,17 +1636,14 @@ async def aspirate96(
       >>> await lh.aspirate96(container, volume=50)
 
     Args:
-      resource (Union[Plate, Container, List[Well]]): Resource object or list of wells.
-      volume (float): The volume to aspirate through each channel
-      offset (Coordinate): Adjustment to where the 96 head should go to aspirate relative to where
-        the plate or container is defined to be. Added to :attr:`default_offset_head96`.
-        Defaults to :func:`Coordinate.zero`.
-      flow_rate ([Optional[float]]): The flow rate to use when aspirating, in ul/s. If `None`, the
+      resource: Resource object or list of wells.
+      volume: The volume to aspirate through each channel
+      offset: Adjustment to where the 96 head should go to aspirate relative to where the plate or container is defined to be. Added to :attr:`default_offset_head96`.  Defaults to :func:`Coordinate.zero`.
+      flow_rate: The flow rate to use when aspirating, in ul/s. If `None`, the
         backend default will be used.
-      liquid_height ([Optional[float]]): The height of the liquid in the well wrt the bottom, in
-        mm. If `None`, the backend default will be used.
-      blow_out_air_volume ([Optional[float]]): The volume of air to aspirate after the liquid, in
-        ul. If `None`, the backend default will be used.
+      liquid_height: The height of the liquid in the well wrt the bottom, in mm. If `None`, the backend default will be used.
+      blow_out_air_volume: The volume of air to aspirate after the liquid, in ul. If `None`, the backend default will be used.
+      mix: A mix operation to perform after the aspiration, optional.
       backend_kwargs: Additional keyword arguments for the backend, optional.
     """
 
@@ -1659,6 +1657,7 @@ async def aspirate96(
       flow_rate=flow_rate,
       liquid_height=liquid_height,
       blow_out_air_volume=blow_out_air_volume,
+      mix=mix,
     )
 
     if not (
@@ -1724,6 +1723,7 @@ async def aspirate96(
         liquid_height=liquid_height,
         blow_out_air_volume=blow_out_air_volume,
         liquids=cast(List[List[Tuple[Optional[Liquid], float]]], all_liquids),  # stupid
+        mix=mix,
       )
     else:  # multiple containers
       # ensure that wells are all in the same plate
@@ -1761,6 +1761,7 @@ async def aspirate96(
         liquid_height=liquid_height,
         blow_out_air_volume=blow_out_air_volume,
         liquids=cast(List[List[Tuple[Optional[Liquid], float]]], all_liquids),  # stupid
+        mix=mix,
       )
 
     try:
@@ -1789,6 +1790,7 @@ async def dispense96(
     flow_rate: Optional[float] = None,
     liquid_height: Optional[float] = None,
     blow_out_air_volume: Optional[float] = None,
+    mix: Optional[Mix] = None,
     **backend_kwargs,
   ):
     """Dispense to all wells in a plate.
@@ -1799,17 +1801,13 @@ async def dispense96(
       >>> await lh.dispense96(plate, volume=50)
 
     Args:
-      resource (Union[Plate, Container, List[Well]]): Resource object or list of wells.
-      volume (float): The volume to dispense through each channel
-      offset (Coordinate): Adjustment to where the 96 head should go to aspirate relative to where
-        the plate or container is defined to be. Added to :attr:`default_offset_head96`.
-        Defaults to :func:`Coordinate.zero`.
-      flow_rate ([Optional[float]]): The flow rate to use when dispensing, in ul/s. If `None`, the
-        backend default will be used.
-      liquid_height ([Optional[float]]): The height of the liquid in the well wrt the bottom, in
-        mm. If `None`, the backend default will be used.
-      blow_out_air_volume ([Optional[float]]): The volume of air to dispense after the liquid, in
-        ul. If `None`, the backend default will be used.
+      resource: Resource object or list of wells.
+      volume: The volume to dispense through each channel
+      offset: Adjustment to where the 96 head should go to aspirate relative to where the plate or container is defined to be. Added to :attr:`default_offset_head96`.  Defaults to :func:`Coordinate.zero`.
+      flow_rate: The flow rate to use when dispensing, in ul/s. If `None`, the backend default will be used.
+      liquid_height: The height of the liquid in the well wrt the bottom, in mm. If `None`, the backend default will be used.
+      blow_out_air_volume: The volume of air to dispense after the liquid, in ul. If `None`, the backend default will be used.
+      mix: If provided, the tip will mix after dispensing.
       backend_kwargs: Additional keyword arguments for the backend, optional.
     """
 
@@ -1823,6 +1821,7 @@ async def dispense96(
       flow_rate=flow_rate,
       liquid_height=liquid_height,
       blow_out_air_volume=blow_out_air_volume,
+      mix=mix,
     )
 
     if not (
diff --git a/pylabrobot/liquid_handling/standard.py b/pylabrobot/liquid_handling/standard.py
index ce94c420df7..3f43830cc45 100644
--- a/pylabrobot/liquid_handling/standard.py
+++ b/pylabrobot/liquid_handling/standard.py
@@ -96,6 +96,7 @@ class MultiHeadAspirationPlate:
   liquid_height: Optional[float]
   blow_out_air_volume: Optional[float]
   liquids: List[List[Tuple[Optional[Liquid], float]]]
+  mix: Optional[Mix]
 
 
 @dataclass(frozen=True)
@@ -108,6 +109,7 @@ class MultiHeadDispensePlate:
   liquid_height: Optional[float]
   blow_out_air_volume: Optional[float]
   liquids: List[List[Tuple[Optional[Liquid], float]]]
+  mix: Optional[Mix]
 
 
 @dataclass(frozen=True)
@@ -120,6 +122,7 @@ class MultiHeadAspirationContainer:
   liquid_height: Optional[float]
   blow_out_air_volume: Optional[float]
   liquids: List[List[Tuple[Optional[Liquid], float]]]
+  mix: Optional[Mix]
 
 
 @dataclass(frozen=True)
@@ -132,6 +135,7 @@ class MultiHeadDispenseContainer:
   liquid_height: Optional[float]
   blow_out_air_volume: Optional[float]
   liquids: List[List[Tuple[Optional[Liquid], float]]]
+  mix: Optional[Mix]
 
 
 class GripDirection(enum.Enum):

From c653f7006e56fbe675edb2124c6c2887c086d790 Mon Sep 17 00:00:00 2001
From: Rick Wierenga <rick_wierenga@icloud.com>
Date: Thu, 2 Oct 2025 18:23:10 -0700
Subject: [PATCH 4/6] fix tests

---
 .../backends/hamilton/STAR_backend.py                | 12 +++++-------
 .../backends/hamilton/vantage_backend.py             |  9 ++++-----
 .../liquid_handling/backends/serializing_backend.py  |  2 ++
 .../liquid_handling/backends/tecan/EVO_tests.py      |  2 ++
 pylabrobot/liquid_handling/liquid_handler.py         |  2 ++
 pylabrobot/liquid_handling/liquid_handler_tests.py   |  4 ++++
 pylabrobot/liquid_handling/standard.py               |  8 ++------
 pylabrobot/server/liquid_handling_api_tests.py       |  1 +
 pylabrobot/server/liquid_handling_server.py          |  5 +++++
 9 files changed, 27 insertions(+), 18 deletions(-)

diff --git a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
index 04270d71939..44aafa6b28e 100644
--- a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
+++ b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
@@ -1827,7 +1827,7 @@ async def aspirate(
     mix_position_from_liquid_surface = _fill_in_defaults(
       mix_position_from_liquid_surface, [0.0] * n
     )
-    mix_speed = [op.mix.flow_rate if op.mix is not None else 0.0 for op in ops]
+    mix_speed = [op.mix.flow_rate if op.mix is not None else 100.0 for op in ops]
     mix_surface_following_distance = _fill_in_defaults(mix_surface_following_distance, [0.0] * n)
     limit_curve_index = _fill_in_defaults(limit_curve_index, [0] * n)
 
@@ -2123,7 +2123,7 @@ async def dispense(
     mix_position_from_liquid_surface = _fill_in_defaults(
       mix_position_from_liquid_surface, [0.0] * n
     )
-    mix_speed = [op.mix.flow_rate if op.mix is not None else 0.0 for op in ops]
+    mix_speed = [op.mix.flow_rate if op.mix is not None else 1.0 for op in ops]
     mix_surface_following_distance = _fill_in_defaults(mix_surface_following_distance, [0.0] * n)
     limit_curve_index = _fill_in_defaults(limit_curve_index, [0] * n)
 
@@ -2281,7 +2281,7 @@ async def aspirate96(
     mix_cycles: int = 0,
     mix_position_from_liquid_surface: float = 0,
     surface_following_distance_during_mix: float = 0,
-    speed_of_mix: float = 120.0,
+    speed_of_mix: float = 0.0,
     limit_curve_index: int = 0,
   ):
     """Aspirate using the Core96 head.
@@ -2400,7 +2400,6 @@ async def aspirate96(
     flow_rate = aspiration.flow_rate or (hlc.aspiration_flow_rate if hlc is not None else 250)
     swap_speed = swap_speed or (hlc.aspiration_swap_speed if hlc is not None else 100)
     settling_time = settling_time or (hlc.aspiration_settling_time if hlc is not None else 0.5)
-    speed_of_mix = speed_of_mix or (hlc.aspiration_mix_flow_rate if hlc is not None else 10.0)
 
     channel_pattern = [True] * 12 * 8
 
@@ -2453,7 +2452,7 @@ async def aspirate96(
       mix_cycles=aspiration.mix.repetitions if aspiration.mix is not None else 0,
       mix_position_from_liquid_surface=round(mix_position_from_liquid_surface * 10),
       surface_following_distance_during_mix=round(surface_following_distance_during_mix * 10),
-      speed_of_mix=round(aspiration.mix.flow_rate * 10) if aspiration.mix is not None else 0,
+      speed_of_mix=round(aspiration.mix.flow_rate * 10) if aspiration.mix is not None else 1200,
       channel_pattern=channel_pattern,
       limit_curve_index=limit_curve_index,
       tadm_algorithm=False,
@@ -2603,7 +2602,6 @@ async def dispense96(
     flow_rate = dispense.flow_rate or (hlc.dispense_flow_rate if hlc is not None else 120)
     swap_speed = swap_speed or (hlc.dispense_swap_speed if hlc is not None else 100)
     settling_time = settling_time or (hlc.dispense_settling_time if hlc is not None else 5)
-    speed_of_mixing = speed_of_mixing or (hlc.dispense_mix_flow_rate if hlc is not None else 100)
 
     channel_pattern = [True] * 12 * 8
 
@@ -2642,7 +2640,7 @@ async def dispense96(
       mixing_cycles=dispense.mix.repetitions if dispense.mix is not None else 0,
       mixing_position_from_liquid_surface=round(mixing_position_from_liquid_surface * 10),
       surface_following_distance_during_mixing=round(surface_following_distance_during_mixing * 10),
-      speed_of_mixing=round(dispense.mix.flow_rate * 10) if dispense.mix is not None else 0,
+      speed_of_mixing=round(dispense.mix.flow_rate * 10) if dispense.mix is not None else 1200,
       channel_pattern=channel_pattern,
       limit_curve_index=limit_curve_index,
       tadm_algorithm=False,
diff --git a/pylabrobot/liquid_handling/backends/hamilton/vantage_backend.py b/pylabrobot/liquid_handling/backends/hamilton/vantage_backend.py
index 6d9d42d51be..8b716a92283 100644
--- a/pylabrobot/liquid_handling/backends/hamilton/vantage_backend.py
+++ b/pylabrobot/liquid_handling/backends/hamilton/vantage_backend.py
@@ -740,7 +740,7 @@ async def aspirate(
       mix_position_in_z_direction_from_liquid_surface=[
         round(mp) for mp in mix_position_in_z_direction_from_liquid_surface or [0] * len(ops)
       ],
-      mix_speed=[round(op.mix.flow_rate * 10) if op.mix is not None else 0 for op in ops],
+      mix_speed=[round(op.mix.flow_rate * 10) if op.mix is not None else 2500 for op in ops],
       surface_following_distance_during_mixing=[
         round(sfdm * 10) for sfdm in surface_following_distance_during_mixing or [0] * len(ops)
       ],
@@ -937,7 +937,7 @@ async def dispense(
       mix_position_in_z_direction_from_liquid_surface=[
         round(mp) for mp in mix_position_in_z_direction_from_liquid_surface or [0] * len(ops)
       ],
-      mix_speed=[round(op.mix.flow_rate * 10) if op.mix is not None else 0 for op in ops],
+      mix_speed=[round(op.mix.flow_rate * 100) if op.mix is not None else 10 for op in ops],
       surface_following_distance_during_mixing=[
         round(sfdm * 10) for sfdm in surface_following_distance_during_mixing or [0] * len(ops)
       ],
@@ -1164,7 +1164,7 @@ async def aspirate96(
       surface_following_distance_during_mixing=round(
         surface_following_distance_during_mixing * 100
       ),
-      mix_speed=round(aspiration.mix.flow_rate * 10) if aspiration.mix is not None else 0,
+      mix_speed=round(aspiration.mix.flow_rate * 10) if aspiration.mix is not None else 20,
       limit_curve_index=limit_curve_index,
       tadm_channel_pattern=tadm_channel_pattern,
       tadm_algorithm_on_off=tadm_algorithm_on_off,
@@ -1287,7 +1287,6 @@ async def dispense96(
     flow_rate = dispense.flow_rate or (hlc.dispense_flow_rate if hlc is not None else 250)
     swap_speed = swap_speed or (hlc.dispense_swap_speed if hlc is not None else 100)
     settling_time = settling_time or (hlc.dispense_settling_time if hlc is not None else 5)
-    mix_speed = mix_speed or (hlc.dispense_mix_flow_rate if hlc is not None else 100)
     type_of_dispensing_mode = type_of_dispensing_mode or _get_dispense_mode(
       jet=jet, empty=empty, blow_out=blow_out
     )
@@ -1329,7 +1328,7 @@ async def dispense96(
         mix_position_in_z_direction_from_liquid_surface * 10
       ),
       surface_following_distance_during_mixing=round(surface_following_distance_during_mixing * 10),
-      mix_speed=round(dispense.mix.flow_rate * 10) if dispense.mix is not None else 0,
+      mix_speed=round(dispense.mix.flow_rate * 10) if dispense.mix is not None else 10,
       limit_curve_index=limit_curve_index,
       tadm_channel_pattern=tadm_channel_pattern,
       tadm_algorithm_on_off=tadm_algorithm_on_off,
diff --git a/pylabrobot/liquid_handling/backends/serializing_backend.py b/pylabrobot/liquid_handling/backends/serializing_backend.py
index 01823eb2347..9c987fffd10 100644
--- a/pylabrobot/liquid_handling/backends/serializing_backend.py
+++ b/pylabrobot/liquid_handling/backends/serializing_backend.py
@@ -108,6 +108,7 @@ async def aspirate(self, ops: List[SingleChannelAspiration], use_channels: List[
         "liquid_height": serialize(op.liquid_height),
         "blow_out_air_volume": serialize(op.blow_out_air_volume),
         "liquids": serialize(op.liquids),
+        "mix": serialize(op.mix),
       }
       for op in ops
     ]
@@ -127,6 +128,7 @@ async def dispense(self, ops: List[SingleChannelDispense], use_channels: List[in
         "liquid_height": serialize(op.liquid_height),
         "blow_out_air_volume": serialize(op.blow_out_air_volume),
         "liquids": serialize(op.liquids),
+        "mix": serialize(op.mix),
       }
       for op in ops
     ]
diff --git a/pylabrobot/liquid_handling/backends/tecan/EVO_tests.py b/pylabrobot/liquid_handling/backends/tecan/EVO_tests.py
index 488d7ccb128..b58c57e1897 100644
--- a/pylabrobot/liquid_handling/backends/tecan/EVO_tests.py
+++ b/pylabrobot/liquid_handling/backends/tecan/EVO_tests.py
@@ -143,6 +143,7 @@ async def test_aspirate(self):
       liquid_height=10,
       blow_out_air_volume=0,
       liquids=[(None, 100)],
+      mix=None,
     )
     await self.evo.aspirate([op], use_channels=[0])
     self.evo.send_command.assert_has_calls(  # type: ignore[attr-defined]
@@ -284,6 +285,7 @@ async def test_dispense(self):
       liquid_height=10,
       blow_out_air_volume=0,
       liquids=[(None, 100)],
+      mix=None,
     )
     await self.evo.dispense([op], use_channels=[0])
     self.evo.send_command.assert_has_calls(  # type: ignore[attr-defined]
diff --git a/pylabrobot/liquid_handling/liquid_handler.py b/pylabrobot/liquid_handling/liquid_handler.py
index 9aee1fc3913..8543f6e71a8 100644
--- a/pylabrobot/liquid_handling/liquid_handler.py
+++ b/pylabrobot/liquid_handling/liquid_handler.py
@@ -1882,6 +1882,7 @@ async def dispense96(
         liquid_height=liquid_height,
         blow_out_air_volume=blow_out_air_volume,
         liquids=cast(List[List[Tuple[Optional[Liquid], float]]], all_liquids),  # stupid
+        mix=mix,
       )
     else:
       # ensure that wells are all in the same plate
@@ -1916,6 +1917,7 @@ async def dispense96(
         liquid_height=liquid_height,
         blow_out_air_volume=blow_out_air_volume,
         liquids=all_liquids,
+        mix=mix,
       )
 
     try:
diff --git a/pylabrobot/liquid_handling/liquid_handler_tests.py b/pylabrobot/liquid_handling/liquid_handler_tests.py
index 328443654c4..ac1880b4db7 100644
--- a/pylabrobot/liquid_handling/liquid_handler_tests.py
+++ b/pylabrobot/liquid_handling/liquid_handler_tests.py
@@ -76,6 +76,7 @@ def _make_asp(
     liquid_height=None,
     blow_out_air_volume=None,
     liquids=[(None, vol)],
+    mix=None,
   )
 
 
@@ -94,6 +95,7 @@ def _make_disp(
     liquid_height=None,
     blow_out_air_volume=None,
     liquids=[(None, vol)],
+    mix=None,
   )
 
 
@@ -841,6 +843,7 @@ async def test_stamp(self):
             liquid_height=None,
             blow_out_air_volume=None,
             liquids=[[(None, 10)]] * 96,
+            mix=None,
           )
         },
       },
@@ -860,6 +863,7 @@ async def test_stamp(self):
             liquid_height=None,
             blow_out_air_volume=None,
             liquids=[[(None, 10)]] * 96,
+            mix=None,
           )
         },
       },
diff --git a/pylabrobot/liquid_handling/standard.py b/pylabrobot/liquid_handling/standard.py
index 3f43830cc45..419502d2cae 100644
--- a/pylabrobot/liquid_handling/standard.py
+++ b/pylabrobot/liquid_handling/standard.py
@@ -59,7 +59,7 @@ class SingleChannelAspiration:
   liquid_height: Optional[float]
   blow_out_air_volume: Optional[float]
   liquids: List[Tuple[Optional[Liquid], float]]
-  mix: Optional[Mix] = None
+  mix: Optional[Mix]
 
 
 @dataclass(frozen=True)
@@ -72,18 +72,14 @@ class SingleChannelDispense:
   liquid_height: Optional[float]
   blow_out_air_volume: Optional[float]
   liquids: List[Tuple[Optional[Liquid], float]]
-  mix: Optional[Mix] = None
+  mix: Optional[Mix]
 
 
 @dataclass(frozen=True)
 class Mix:
-  # resource: Container
-  # offset: Coordinate
-  # tip: Tip
   volume: float
   repetitions: int
   flow_rate: float
-  # liquid_height: float
 
 
 @dataclass(frozen=True)
diff --git a/pylabrobot/server/liquid_handling_api_tests.py b/pylabrobot/server/liquid_handling_api_tests.py
index 57bc98b121e..1016ede84f9 100644
--- a/pylabrobot/server/liquid_handling_api_tests.py
+++ b/pylabrobot/server/liquid_handling_api_tests.py
@@ -220,6 +220,7 @@ def test_aspirate(self):
           "use_channels": [0],
         },
       )
+      print(task)
       response = _wait_for_task_done(self.base_url, client, task.json.get("id"))
       self.assertEqual(response.json.get("status"), "succeeded")
       self.assertEqual(response.status_code, 200)
diff --git a/pylabrobot/server/liquid_handling_server.py b/pylabrobot/server/liquid_handling_server.py
index 486cacc2a9b..4882f8ccfd7 100644
--- a/pylabrobot/server/liquid_handling_server.py
+++ b/pylabrobot/server/liquid_handling_server.py
@@ -26,6 +26,7 @@
 )
 from pylabrobot.liquid_handling.standard import (
   Drop,
+  Mix,
   Pickup,
   SingleChannelAspiration,
   SingleChannelDispense,
@@ -234,6 +235,7 @@ async def aspirate():
         List[Tuple[Optional[Liquid], float]],
         deserialize(sc["liquids"]),
       )
+      mix = Mix(**sc["mix"]) if sc.get("mix") is not None else None
       aspirations.append(
         SingleChannelAspiration(
           resource=resource,
@@ -244,6 +246,7 @@ async def aspirate():
           liquid_height=liquid_height,
           blow_out_air_volume=blow_out_air_volume,
           liquids=liquids,
+          mix=mix,
         )
       )
     use_channels = data["use_channels"]
@@ -290,6 +293,7 @@ async def dispense():
         List[Tuple[Optional[Liquid], float]],
         deserialize(sc["liquids"]),
       )
+      mix = Mix(**sc["mix"]) if sc.get("mix") is not None else None
       dispenses.append(
         SingleChannelDispense(
           resource=resource,
@@ -300,6 +304,7 @@ async def dispense():
           liquid_height=liquid_height,
           blow_out_air_volume=blow_out_air_volume,
           liquids=liquids,
+          mix=mix,
         )
       )
     use_channels = data["use_channels"]

From 9d0993eb8b07db0c378bc60f842af702c9276f96 Mon Sep 17 00:00:00 2001
From: Rick Wierenga <rick_wierenga@icloud.com>
Date: Thu, 2 Oct 2025 22:24:16 -0700
Subject: [PATCH 5/6] x

---
 .../liquid_handling/backends/serializing_backend_tests.py     | 2 ++
 pylabrobot/liquid_handling/liquid_handler.py                  | 4 ++--
 pylabrobot/plate_reading/imager.py                            | 2 +-
 pylabrobot/plate_reading/standard.py                          | 2 +-
 pylabrobot/server/liquid_handling_api_tests.py                | 2 +-
 5 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/pylabrobot/liquid_handling/backends/serializing_backend_tests.py b/pylabrobot/liquid_handling/backends/serializing_backend_tests.py
index 0884f219b95..3063a8d7c62 100644
--- a/pylabrobot/liquid_handling/backends/serializing_backend_tests.py
+++ b/pylabrobot/liquid_handling/backends/serializing_backend_tests.py
@@ -105,6 +105,7 @@ async def test_aspirate(self):
             "liquid_height": None,
             "blow_out_air_volume": None,
             "liquids": [[None, 10]],
+            "mix": None,
           }
         ],
         "use_channels": [0],
@@ -133,6 +134,7 @@ async def test_dispense(self):
             "liquid_height": None,
             "blow_out_air_volume": None,
             "liquids": [[None, 10]],
+            "mix": None,
           }
         ],
         "use_channels": [0],
diff --git a/pylabrobot/liquid_handling/liquid_handler.py b/pylabrobot/liquid_handling/liquid_handler.py
index 8543f6e71a8..767e7cd0a22 100644
--- a/pylabrobot/liquid_handling/liquid_handler.py
+++ b/pylabrobot/liquid_handling/liquid_handler.py
@@ -976,7 +976,7 @@ async def aspirate(
         tips,
         blow_out_air_volume,
         liquids,
-        mix or [None] * len(use_channels),
+        mix or [None] * len(use_channels),  # type: ignore
       )
     ]
 
@@ -1209,7 +1209,7 @@ async def dispense(
         tips,
         blow_out_air_volume,
         liquids,
-        mix or [None] * len(use_channels),
+        mix or [None] * len(use_channels),  # type: ignore
       )
     ]
 
diff --git a/pylabrobot/plate_reading/imager.py b/pylabrobot/plate_reading/imager.py
index d67ecb6b887..f933a572551 100644
--- a/pylabrobot/plate_reading/imager.py
+++ b/pylabrobot/plate_reading/imager.py
@@ -29,7 +29,7 @@
   _CV2_IMPORT_ERROR = e
 
 try:
-  import numpy as np
+  import numpy as np  # type: ignore
 except ImportError:
   np = None  # type: ignore[assignment]
 
diff --git a/pylabrobot/plate_reading/standard.py b/pylabrobot/plate_reading/standard.py
index a85d44a7e16..263f8b6e398 100644
--- a/pylabrobot/plate_reading/standard.py
+++ b/pylabrobot/plate_reading/standard.py
@@ -3,7 +3,7 @@
 from typing import Awaitable, Callable, List, Literal, Union
 
 try:
-  import numpy.typing as npt
+  import numpy.typing as npt  # type: ignore
 
   Image = npt.NDArray
 except ImportError:
diff --git a/pylabrobot/server/liquid_handling_api_tests.py b/pylabrobot/server/liquid_handling_api_tests.py
index 1016ede84f9..f42846ef614 100644
--- a/pylabrobot/server/liquid_handling_api_tests.py
+++ b/pylabrobot/server/liquid_handling_api_tests.py
@@ -203,7 +203,7 @@ def test_aspirate(self):
           "channels": [
             {
               "resource_name": well.name,
-              "volume": 10,
+              "volume": 10.0,
               "tip": serialize(tip),
               "offset": {
                 "type": "Coordinate",

From bf4eddee1b862945691b5176598ee391c8e4fc8d Mon Sep 17 00:00:00 2001
From: Rick Wierenga <rick_wierenga@icloud.com>
Date: Thu, 2 Oct 2025 22:34:33 -0700
Subject: [PATCH 6/6] wtf

---
 pylabrobot/plate_reading/standard.py              | 10 ++++++++--
 pylabrobot/thermocycling/opentrons_backend_usb.py | 10 +++++-----
 2 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/pylabrobot/plate_reading/standard.py b/pylabrobot/plate_reading/standard.py
index 263f8b6e398..f2d3f731a01 100644
--- a/pylabrobot/plate_reading/standard.py
+++ b/pylabrobot/plate_reading/standard.py
@@ -1,13 +1,19 @@
 import enum
+import sys
 from dataclasses import dataclass
 from typing import Awaitable, Callable, List, Literal, Union
 
+if sys.version_info >= (3, 10):
+  from typing import TypeAlias
+else:
+  from typing_extensions import TypeAlias
+
 try:
   import numpy.typing as npt  # type: ignore
 
-  Image = npt.NDArray
+  Image: TypeAlias = npt.NDArray
 except ImportError:
-  Image = object  # type: ignore
+  Image: TypeAlias = object  # type: ignore
 
 
 class Objective(enum.Enum):
diff --git a/pylabrobot/thermocycling/opentrons_backend_usb.py b/pylabrobot/thermocycling/opentrons_backend_usb.py
index c6c8ec1910d..41daf9a002c 100644
--- a/pylabrobot/thermocycling/opentrons_backend_usb.py
+++ b/pylabrobot/thermocycling/opentrons_backend_usb.py
@@ -13,9 +13,9 @@
 
 try:
   import serial.tools.list_ports
-  from opentrons.drivers.thermocycler import ThermocyclerDriverFactory
-  from opentrons.drivers.thermocycler.abstract import AbstractThermocyclerDriver
-  from opentrons.drivers.types import ThermocyclerLidStatus
+  from opentrons.drivers.thermocycler import ThermocyclerDriverFactory  # type: ignore
+  from opentrons.drivers.thermocycler.abstract import AbstractThermocyclerDriver  # type: ignore
+  from opentrons.drivers.types import ThermocyclerLidStatus  # type: ignore
 
   USE_OPENTRONS_DRIVER = True
   _import_error = None
@@ -274,7 +274,7 @@ async def deactivate_lid(self):
 
   async def get_device_info(self) -> dict:
     assert self._driver is not None
-    return await self._driver.get_device_info()
+    return await self._driver.get_device_info()  # type: ignore
 
   async def get_block_current_temperature(self) -> List[float]:
     assert self._driver is not None
@@ -304,7 +304,7 @@ async def get_lid_open(self) -> bool:
     """Return True if the lid is open."""
     assert self._driver is not None
     lid_status = await self._driver.get_lid_status()
-    return lid_status == ThermocyclerLidStatus.OPEN
+    return lid_status == ThermocyclerLidStatus.OPEN  # type: ignore
 
   async def get_lid_status(self) -> LidStatus:
     assert self._driver is not None